1. What will taenia cause? Intestinal obstruction 2. A patient have renal stone, hypercalcemia, increase PTH-- Parathyroid hyperplasia Parathyroid benign Parathyroid metaplastic 3. Chronic cervititis, dyspareunia, whitish vaginal discharge Edema of subepithelial matrix-- Hemorrhage of submucosal lesion Reactive atypia of endocervical epithelium Mononuclear cells infiltrate in squamo-columnar junction 4. 8cm tetranoma, skin, hair, teeth, ovarian cyst Mature cystic tetranoma 5. Diagnosis of leprosy Acid fast stain skin scraping 6. Prednisolone (steroid) for crohn disese, leads to Hypocalcemia 7. Prion disease, due to: Mutation of cellular protein gene 8. Backward design Case control 9. Acute cholecystitis Jaundice 10. A children have leukemia, what vaccine should be prohibited Mumps vaccine 11. Smoker, diabetic, GERD, gastric reflux, redness at lower end of esophagus, diagnosed as esophagitis, due to?---- Gastric acid Tobacco HSV Candida sp. 12. Antiepileptic drugs side effect Nystagmus 13. Casts found in acute pyelonephritis---- RBC cast WBC cast Granular cast Fatty cast 14. Opiod is contradict with undiagnosed abdominal pain, this is because---- Prevent masking of visceral pain Obstruction of blood flow Damage to internal organ Abdominal perforation 15. Alkaline, yellow MacConkey, gram negative, bacilli, positive urease test Proteus sp 16. Diabteic, dyslipidemia, middle cerebral artery infarct Atherosclerosis 17. According to the National Health & Morbidity Survey 2015, NCD accounted for 74% of deaths in Malaysia. Which of the following causes the most deaths in Malaysian hospitals?---- Diseases of circulatory system Diseases of the respiratory system Neoplasms Diseases of digestive system 18. Epithelial neoplastic, post-menopausal bleeding, ulcers, no mass Choriocarcinoma 19. Increase gentamicin, inhibit DNA gyrease, hematuria, renal insufficiency, iatrogenic nephrotoxicity, complication? Thrombotic microangiopathy 20. Oxytocin contraindicated with?---- History in gestational diabetes History in eclampsia History in caeserean section Early rupture of membrane 21. Spironolactone (potassium sparing) acts on Collecting duct-- Loop of Henle Distal convoluted tubule Proximal convoluted tubule 22. Patient has edema, spikes in the basement membrane, proteinuria, which of the following statements is correct? Subepithelial immune deposit complex 23. Antihelminth drug, filiarasis, which drug should be given? Praziquantel 24. Patient has IDC (invasive ductal carcinoma), positive HER2, what drug should be given? Tamoxifen 25. 13 y/o boy has testicular pain after evaluation, he is suspect to have---- Testicular torsion Orchitis Epididymitis Testicular tumor 26. Disease is not an inevitable outcome of the host-pathogen interaction and, furthermore, pathogens can express a wide range of virulence. Which of the following statements best describe virulence for the above scenario?---- Ability to cause clinical disease Ability to evoke an immune response Ability to cause severe disease Ability to cause death Candida albicans 27. Patient undergo examination, found out thick, cheese cottage discharge, she is suspected with the infection of: 28. Patient is diagnosed as tetanus, infected by clostridium tetani, which examination should be carried out? Wound swab 29. Patient has increased pigmentation in the oral mucosa, decreased sodium level with increased potassium level, increase in cortical ACTH, he is diagnosed with adrenal insufficiency, which of the following statements matches? Waterhouse-Friderichsen Selective (SAOR) 30. Anovulatory infertility, she is treated with clomiphene, which of the following best describe the MOA---- Inhibit FSH release Inhibit estrogen receptor synthesis Down regulated GnRH 31. Increased T3, T4, decrease TSH, diagnosed as Graves disease, microscopy appearance: Scalloped 32. HIV, early stage Protein 17 33. A 56 y/o Schizophrenia patient on haloperidol presents with symptoms of tardive dyskinesia. The psychiatrist decides to change her medication to clozapine. Which of the following pharmacological action of cloazapine best explains the change of drug? Has a low affinity of for dopamine D2 receptors-- Has greater antagonist at muscurinic receptors Blocks dopamine release Activates GABA receptos 34. How do HPV warts occur? HPV infects surface layer of epithelium 35. A malnourished 2 y/o (weight 4.75kg) is undergoing the proper nutritional programme who gains 32% more weight in three weeks (weight 6.28kg). Which of the following is the most accurate direct nutritional status assessment?---- Clinical examination Biochemical examination Anthropometry Vital statistics 36. Dysentery diarrhea, pear shaped, what is the causative agent? Giardia lambia (watery)-- Entamoeba histolytica Entamoeba coli Balantidium coli 37. Obstructive uropathy, narrow right ureter, scarring, hydronephrosis, polyuria Decrease in glomerular filtration 38. Jaundice, increased IgM, diagnosed as Hepatitis E, why? Complement activation 39. Peutz Jeghers Polyps, mutation STK 11 Superficial columnar & goblet 40. Diffuse infiltrative malignant neoplasm Adenocarcinoma 41. A patient has rabies, fast spreading to CNS, due to: Migration of infected epidermal dendritic cell 42. Infective stage of fasciola Cercaeria 43. P value 0.4 44. Increase extracellular fluid, increase permeability, affect interstitial space Vasogenic edema 45. Entamoeba histolytica, in order to eradicate cyst, treated with? Metronidazole 46. Maternal mortality rate indicate level of health system development, this is because of: Maternal death irrespective of duration of pregnancy 47. Hematuria, solidarity nodular mass lesion, cluster of pleomorohic malignant cells Clear cell carcinoma 48. Epidermiologists have identified the epidemiologic triad of diseases as a traditional model of infectious disease causation. Which of the following combinations is the component of the epidemiological triad? Agent, host, environment -- Primary prevention, secondary prevention, tertiary prevention Time, place, person Souce, mode of transmission, susceptible host 49. Fixed short breathe, dyscrasias, dysentery treated by sulphanethoxazole Sulphur drug induced anemia 50. Schistosoma haematobium, investigation Urine examination 51. CNS demyelination, leg weakness, oligoclonal band, Autoimmune demyelination Abrupt withdrawal 52. Systemic lupus erythematosus is treated with corticosteroid, leads to rebound hypertension, due to:---- Psycho depend Hyperglycaemia Acute adrenal insufficiency Somatotropin 53. A 3 y/o girl presents to the Pediatric Clinic with short stature and appears to have loose skin on her neck. Cytogenetic testing reveals an XO karyotype - (Turner syndrome). Which of the following drugs is the most likely for her to achieve appropriate heigh for her age?---- Growth hormone-releasing hormone (GHRH) Adrenocorticotropin Corticotropin-releasing hormone (CRH) 54. Campylobacter jejuni virulence factor cause inflammation Adhesins 55. Type 1 diabetes mellitus treated by insulin, avoid the same injection side, why? Lipodystrophy 56. Insomnia, anxiety, increase inhibitory effect of GABA on neuronal excitability, should be treated with? Benzodiazepine: increase chloride influx, increase negative charge, alter voltage, brain resist nerve impulse 57. Hypopituitarism, non-functional pituitary adenoma, which one will be the first affected?---- Breast Ovary Thyroid Cortex 58. A patient has gradual hearing loss, sensorineural hearing loss, cell circumscribed neoplasm at cerebellopontine angle at posterior cervical fosa, microscopic shows Antoni A & B and verocay necrosis, which cells are affected? Schawann cells 59. Meningitis infected by Cryptococcus neoformas, treated with amphotericin B + flucytosine, why combination drugs? Prevent resistance to antifungal 60. Painful genital, diagnosed with chancroid, diagnostic test? Nucleic acid probe: to test chancroid CA (hemophilus ducreyi write full questions for all 60..n explain the ans

Reading File

Given the large scope (60 MCQs), I'll answer all from my medical knowledge directly, providing complete questions and full explanations for each.

60 MCQ - Complete Questions & Explained Answers

Q1. Taenia (tapeworm) infestation most commonly leads to which complication?

A) Liver abscess
B) Intestinal obstruction ✓
C) Renal failure
D) Pneumonia

Answer: Intestinal obstruction Taenia species (T. solium, T. saginata) are large intestinal cestodes. Heavy worm burdens can cause mechanical blockage of the intestinal lumen leading to obstruction. T. solium larvae (cysticercosis) can also cause CNS symptoms, but the classic direct complication of the adult worm is intestinal obstruction.

Q2. A patient presents with renal stones, hypercalcemia, and elevated PTH. What is the most likely diagnosis?

A) Parathyroid hyperplasia/benign adenoma ✓
B) Parathyroid metaplasia
C) Parathyroid carcinoma
D) Vitamin D toxicity

Answer: Parathyroid benign adenoma (Primary Hyperparathyroidism) The triad of hypercalcemia + elevated PTH + nephrolithiasis (renal stones) is classic for primary hyperparathyroidism. The most common cause (~85%) is a benign parathyroid adenoma (solitary). Parathyroid hyperplasia accounts for ~15% and is associated with MEN syndromes. Malignant parathyroid carcinoma is rare (<1%). In primary hyperparathyroidism, PTH is inappropriately elevated for the calcium level, driving osteoclast activity and hypercalcemia, with calcium spilling into urine causing stones.

Q3. A patient with chronic cervicitis presents with dyspareunia and whitish vaginal discharge. Histology shows changes at the squamo-columnar junction. What is the most characteristic microscopic finding?

A) Edema of subepithelial matrix
B) Hemorrhage of submucosal lesion
C) Reactive atypia of endocervical epithelium
D) Mononuclear cell infiltrate at the squamo-columnar junction ✓

Answer: Mononuclear cell infiltrate at the squamo-columnar junction Chronic cervicitis is characterized histologically by a chronic inflammatory infiltrate - predominantly lymphocytes, plasma cells, and macrophages (mononuclear cells) - concentrated at the squamo-columnar junction (transformation zone). The squamo-columnar junction is most susceptible to infection and metaplastic change. Reactive atypia can be seen but is a secondary change. Edema and hemorrhage are features of acute cervicitis.

Q4. An 8 cm ovarian cyst in a woman contains skin, hair, and teeth. What is the diagnosis?

A) Immature teratoma
B) Dysgerminoma
C) Mature cystic teratoma (dermoid cyst) ✓
D) Serous cystadenoma

Answer: Mature cystic teratoma (dermoid cyst) A cystic ovarian mass containing ectodermal derivatives - skin, hair, teeth, sebaceous material - is pathognomonic of a mature cystic teratoma (dermoid cyst). These are the most common ovarian germ cell tumors in women of reproductive age, arising from all three germ layers but predominantly ectodermal. They are benign (unlike immature teratomas). The presence of a Rokitansky protuberance (dermal plug) is characteristic on imaging and gross pathology.

Q5. Which investigation is the gold standard for diagnosing leprosy (Mycobacterium leprae)?

A) Blood culture
B) PCR
C) Acid-fast stain of skin scraping (slit-skin smear) ✓
D) ELISA

Answer: Acid-fast stain of skin scraping (slit-skin smear) M. leprae cannot be cultured in vitro. The standard diagnostic method is the slit-skin smear - skin scrapings from lesions (earlobes, nasal septum, affected skin) stained with Ziehl-Neelsen (acid-fast) stain to demonstrate red acid-fast bacilli. The bacterial index (BI) and morphological index (MI) quantify bacillary load. In paucibacillary (tuberculoid) leprosy, smears may be negative - skin biopsy becomes essential. PCR is increasingly used but slit-skin smear remains the field standard.

Q6. A patient with Crohn's disease is treated with prednisolone (corticosteroid). What metabolic complication is expected?

A) Hypocalcemia ✓
B) Hyperkalemia
C) Hypoglycemia
D) Hyponatremia

Answer: Hypocalcemia (and osteoporosis) Corticosteroids such as prednisolone cause hypocalcemia through multiple mechanisms:

Decrease intestinal calcium absorption (antagonize vitamin D action on gut)
Increase renal calcium excretion
Inhibit osteoblast activity, reduce bone formation
Stimulate PTH secretion (secondary hyperparathyroidism)

The net result is decreased serum calcium, reduced bone density (osteoporosis), and increased fracture risk. This is why calcium and vitamin D supplementation is recommended for patients on long-term steroids.

Q7. Prion disease (e.g., Creutzfeldt-Jakob disease) is caused by:

A) Viral infection
B) Bacterial toxin
C) Mutation of cellular protein gene (PrP gene) ✓
D) Autoimmune destruction

Answer: Mutation of cellular protein gene Prion diseases are caused by misfolded prion proteins (PrPSc) that convert normal cellular prion protein (PrPC) into the abnormal isoform. The gene encoding PrP is PRNP on chromosome 20. Familial prion diseases (e.g., familial CJD, Gerstmann-Straussler-Scheinker syndrome, Fatal Familial Insomnia) result from mutations in the PRNP gene. The misfolded protein is protease-resistant, accumulates in neurons, and is infectious. Prions contain no nucleic acid - they are purely proteinaceous infectious particles.

Q8. A study design that identifies people with a disease and compares them with controls to find past exposures is called:

A) Cohort study
B) Case-control study ✓ (Backward design = retrospective)
C) Randomized controlled trial
D) Cross-sectional study

Answer: Case-control study "Backward design" refers to case-control studies, which work retrospectively - starting with the outcome (disease) and looking backward for exposure. Cases (people with disease) are compared to controls (without disease) for prior exposures. This is in contrast to cohort studies which are "forward design" (exposure → outcome). Case-control studies are efficient for rare diseases and have odds ratio as their measure of association.

Q9. Which of the following is NOT a typical feature of acute cholecystitis?

A) Right upper quadrant pain
B) Murphy's sign
C) Jaundice ✓ (not typical of simple cholecystitis)
D) Fever

Answer: Jaundice (is NOT typical of uncomplicated acute cholecystitis) Acute cholecystitis is inflammation of the gallbladder, usually from a gallstone obstructing the cystic duct. Classic features: RUQ/epigastric pain, fever, nausea/vomiting, Murphy's sign. Jaundice is NOT a typical feature because the common bile duct is not obstructed. Jaundice occurs in complications: Mirizzi syndrome (stone compressing CBD), choledocholithiasis (stone in CBD), or cholangitis (Charcot's triad). The question implies jaundice is an incorrect/unexpected finding.

Q10. A child with leukemia (immunocompromised) needs vaccinations. Which vaccine is CONTRAINDICATED?

A) Inactivated polio vaccine
B) MMR/Mumps vaccine ✓
C) Hepatitis B vaccine
D) Tetanus toxoid

Answer: Mumps vaccine (live attenuated - contraindicated) The MMR vaccine (measles, mumps, rubella) is a live attenuated vaccine. In immunocompromised patients (leukemia, on chemotherapy), live vaccines are absolutely contraindicated because the attenuated organism can cause disseminated disease. Other contraindicated live vaccines include: varicella (VZV), LAIV (nasal flu), BCG, oral typhoid (Ty21a), oral polio (OPV), yellow fever, and rotavirus. Inactivated vaccines (IPV, hepatitis B, Tdap, pneumococcal) are generally safe.

Q11. A smoker with diabetes and GERD presents with redness and inflammation at the lower esophagus. What is the most likely cause of esophagitis?

A) Gastric acid (reflux esophagitis) ✓
B) Tobacco
C) HSV
D) Candida sp.

Answer: Gastric acid (reflux esophagitis) This patient has multiple risk factors for GERD (smoking, diabetes causing gastroparesis, obesity). The redness at the lower end of the esophagus with a background of GERD and gastric reflux points to reflux esophagitis caused by gastric acid. While tobacco worsens GERD (reduces LES tone), it is not the direct cause of the mucosal damage. HSV esophagitis causes painful vesicles/ulcers (in immunocompromised). Candida esophagitis causes white plaques with odynophagia (in immunocompromised). The described "redness" (erythema) at the lower end is classic for acid-induced reflux esophagitis.

Q12. Which side effect is characteristically associated with antiepileptic drugs (especially phenytoin)?

A) Bradycardia
B) Nystagmus ✓
C) Hearing loss
D) Renal failure

Answer: Nystagmus Phenytoin toxicity classically presents as: Nystagmus (earliest sign at toxic levels), then ataxia, then diplopia, then altered mental status/encephalopathy (at high levels). The mnemonic is N-A-D (Nystagmus → Ataxia → Drowsiness) with increasing toxicity. Carbamazepine also causes nystagmus and diplopia. Valproate is associated with hepatotoxicity and weight gain. Nystagmus can also occur with phenobarbital and other CNS depressants.

Q13. A patient with acute pyelonephritis has urinalysis done. Which cast is most likely to be found?

A) RBC cast (glomerulonephritis)
B) WBC cast ✓
C) Granular cast (chronic renal disease)
D) Fatty cast (nephrotic syndrome)

Answer: WBC cast (leukocyte cast) WBC casts are pathognomonic of upper urinary tract infection - specifically acute pyelonephritis or acute interstitial nephritis. They form when white blood cells are trapped in the tubular lumen and coalesce with Tamm-Horsfall protein. Their presence distinguishes pyelonephritis from lower UTI (cystitis). Other cast associations:

RBC casts → glomerulonephritis
Fatty casts → nephrotic syndrome
Granular/waxy casts → chronic kidney disease
Hyaline casts → normal/dehydration

Q14. Opioids are traditionally contraindicated in undiagnosed acute abdominal pain. Why?

A) Prevent masking of visceral pain (and physical signs) ✓
B) Obstruction of blood flow
C) Damage to internal organs
D) Risk of abdominal perforation

Answer: Prevent masking of visceral pain The traditional concern is that opioids would mask pain and physical signs (rebound tenderness, guarding), potentially hiding a serious diagnosis like appendicitis, bowel perforation, or ischemic bowel. However, current evidence and modern guidelines (including ACE/ACEP) suggest this dogma is outdated - opioid analgesia in acute abdominal pain does NOT significantly impair diagnostic accuracy and is humane. Despite this, the exam answer remains "masking of visceral pain" in the classical teaching context.

Q15. An alkaline, yellow colony on MacConkey agar, gram-negative bacillus with a positive urease test is most likely:

A) E. coli
B) Klebsiella
C) Proteus sp. ✓
D) Pseudomonas

Answer: Proteus sp. Proteus is characterized by:

Gram-negative rod
Strong urease positive (splits urea → ammonia → alkaline urine → favors struvite stone formation)
Non-lactose fermenter → pale/colorless on MacConkey (though colonies can be yellow/alkaline)
Swarming motility on blood agar (distinctive)
Associated with UTIs and urinary tract stones
H2S production positive

Klebsiella is urease positive but a lactose fermenter (pink on MacConkey). H. pylori is also strongly urease positive but is a curved gram-negative rod found in the stomach.

Q16. A diabetic, dyslipidemic patient suffers a middle cerebral artery infarct. What is the underlying mechanism?

A) Cardioembolic stroke
B) Atherosclerosis ✓
C) Vasculitis
D) Venous thrombosis

Answer: Atherosclerosis Diabetes mellitus and dyslipidemia are major risk factors for atherosclerosis - the accumulation of lipid-laden plaques in arterial walls. In the cerebral circulation, atherosclerotic plaques develop in large vessels (MCA, ICA, basilar artery), causing thrombotic stroke through:

Plaque rupture → local thrombosis
Progressive luminal narrowing → ischemia
Artery-to-artery embolism

The MCA territory is the most common site for ischemic stroke. Atherosclerosis is accelerated in diabetes (endothelial dysfunction, advanced glycation end products) and dyslipidemia (LDL oxidation).

Q17. According to the National Health & Morbidity Survey (NHMS) 2015, NCDs account for 74% of deaths in Malaysia. What is the leading cause of death in Malaysian hospitals?

A) Diseases of the circulatory system ✓
B) Diseases of the respiratory system
C) Neoplasms
D) Diseases of the digestive system

Answer: Diseases of the circulatory system According to Malaysian health statistics (NHMS 2015 and Ministry of Health Malaysia data), diseases of the circulatory system (ischemic heart disease, stroke, heart failure) are consistently the leading cause of hospital deaths in Malaysia, accounting for a large proportion of NCD mortality. This reflects the high burden of cardiovascular risk factors in Malaysia: hypertension (~30%), diabetes (~17%), obesity (~17%), and dyslipidemia (~47%).

Q18. A post-menopausal woman presents with vaginal bleeding. Examination shows ulcers but no discrete mass. Histology reveals epithelial neoplastic cells. What is the most likely diagnosis?

A) Endometrial polyp
B) Cervical carcinoma
C) Endometrial carcinoma ✓ (or choriocarcinoma as listed)
D) Vaginal atrophy

Answer: Endometrial carcinoma (or Choriocarcinoma as listed) Post-menopausal bleeding + ulcerative epithelial neoplasm = endometrial carcinoma until proven otherwise. However, the listed answer is choriocarcinoma - a highly malignant gestational trophoblastic tumor that can occur post-menopausally (from prior pregnancy), produces marked bleeding, shows no discrete mass (infiltrative), and presents with neoplastic epithelial (trophoblastic) cells on biopsy. Choriocarcinoma would also show markedly elevated beta-hCG. If "epithelial neoplastic" refers to malignant trophoblast, choriocarcinoma fits.

Q19. A patient with increased gentamicin levels and concurrent use of a DNA gyrase inhibitor (fluoroquinolone) develops hematuria and renal insufficiency. What is the complication?

A) Acute tubular necrosis
B) Thrombotic microangiopathy ✓
C) IgA nephropathy
D) Renal papillary necrosis

Answer: Thrombotic microangiopathy (TMA) Some fluoroquinolones (DNA gyrase inhibitors) have been associated with thrombotic microangiopathy, a condition involving microvascular endothelial injury, thrombocytopenia, microangiopathic hemolytic anemia, and renal impairment. Gentamicin is nephrotoxic (proximal tubule damage). The combination can produce severe iatrogenic nephrotoxicity. TMA is characterized by microthrombi in small vessels causing hematuria and acute renal insufficiency.

Q20. Oxytocin (used for labor induction) is most importantly contraindicated in which situation?

A) History of gestational diabetes
B) History of eclampsia
C) History of caesarean section (previous uterine scar) ✓
D) Early rupture of membranes

Answer: History of caesarean section Oxytocin is contraindicated (or used with extreme caution) in patients with a previous caesarean section (uterine scar) because it increases uterine contractility and can precipitate uterine rupture - a life-threatening complication. This is also true for grand multipara, malpresentation, and cephalopelvic disproportion. Among the options, a scarred uterus from C-section carries the highest risk of uterine rupture with oxytocin use.

Q21. Spironolactone (potassium-sparing diuretic) acts primarily at which nephron segment?

A) Loop of Henle
B) Collecting duct (and distal convoluted tubule) ✓
C) Proximal convoluted tubule
D) Bowman's capsule

Answer: Collecting duct (principal cells) Spironolactone is a competitive aldosterone antagonist. It acts on the cortical collecting duct (CCD) and late distal convoluted tubule, where aldosterone normally binds to mineralocorticoid receptors in principal cells to:

Upregulate Na+/K+ ATPase and ENaC (sodium reabsorption)
Increase K+ and H+ secretion

Spironolactone blocks this → decreased Na+ reabsorption, decreased K+ excretion (hyperkalemia risk), decreased H+ excretion. Loop diuretics act at the thick ascending limb of Henle.

Q22. A patient has edema, proteinuria, and renal biopsy shows "spike and dome" pattern (spikes in the basement membrane) on silver stain. What is the most likely finding on immunofluorescence?

A) Linear IgG deposits (Goodpasture)
B) Subepithelial immune complex deposits ✓
C) Mesangial deposits
D) Subendothelial deposits

Answer: Subepithelial immune complex deposits The "spike and dome" pattern on silver stain + nephrotic syndrome (edema + proteinuria) is classic for Membranous Nephropathy. The "spikes" are GBM projections between immune deposits, and the "domes" are the deposits themselves - subepithelial immune complex deposits containing IgG and C3 on immunofluorescence. Primary membranous nephropathy is caused by anti-PLA2R antibodies. Secondary causes: hepatitis B, malignancy, SLE, drugs (penicillamine, gold).

Q23. A patient with filariasis (lymphatic filariasis) requires treatment. Which antihelminthic drug is indicated?

A) Diethylcarbamazine (DEC) ✓ (but Praziquantel listed)
B) Praziquantel
C) Albendazole
D) Mebendazole

Answer: Note on listed answer (Praziquantel) The listed answer is praziquantel, but the correct drug for filariasis (Wuchereria bancrofti, Brugia malayi) is diethylcarbamazine (DEC), often combined with albendazole or ivermectin. Praziquantel is used for trematodes (schistosomiasis, liver flukes, lung flukes) and cestodes (tapeworms). This appears to be an error in the provided answer. The correct antifilarial drug is DEC.

Q24. A patient has invasive ductal carcinoma (IDC) of the breast, HER2-positive. What is the appropriate targeted therapy?

A) Trastuzumab (Herceptin) ✓ (not Tamoxifen)
B) Tamoxifen
C) Anastrozole
D) Cyclophosphamide alone

Answer: Note - Trastuzumab, not Tamoxifen HER2-positive breast cancer is treated with trastuzumab (Herceptin) - a monoclonal antibody targeting the HER2 receptor. Tamoxifen is used for estrogen receptor-positive (ER+) breast cancer (SERM - blocks estrogen receptors). If the tumor is HER2+ only (ER-), tamoxifen would not be indicated. The correct answer for HER2+ IDC is trastuzumab ± pertuzumab. The listed answer (tamoxifen) appears incorrect unless the tumor is also ER+.

Q25. A 13-year-old boy presents with acute testicular pain. After evaluation, what is the most likely diagnosis?

A) Testicular torsion ✓
B) Orchitis (more common in post-pubertal with mumps)
C) Epididymitis (more common in sexually active adults)
D) Testicular tumor (usually painless)

Answer: Testicular torsion In a 13-year-old adolescent with acute testicular pain, testicular torsion is the most likely diagnosis and a urological emergency. Peak incidence: neonatal and 12-18 years (bell-clapper deformity predisposes). The testicle twists on the spermatic cord → venous then arterial obstruction → ischemia → infarction within 6 hours. Time is critical: detorsion within 6h salvage rate ~100%, >24h ~10%. Epididymitis is more common in sexually active men. Orchitis (viral) is associated with mumps. Tumors are typically painless masses.

Q26. "Disease is not an inevitable outcome of host-pathogen interaction, and pathogens express a wide range of virulence." Which statement best describes virulence?

A) Ability to cause clinical disease ✓
B) Ability to evoke immune response
C) Ability to cause severe disease (= severity of virulence)
D) Ability to cause death (= lethality)

Answer: Ability to cause clinical disease Virulence is defined as the relative ability of a pathogen to cause disease in a host - it is the quantitative measure of pathogenicity. It is distinct from:

Pathogenicity: capacity to cause disease (qualitative)
Infectivity: ability to establish infection
Invasiveness: ability to spread in tissues
Toxigenicity: ability to produce toxins
Lethality: ability to cause death

The statement that "disease is not inevitable" reflects that virulence exists on a spectrum - some pathogens cause subclinical infection while others cause severe clinical disease.

Q27. A patient presents with thick, cottage-cheese-like vaginal discharge. She is suspected of infection with:

A) Trichomonas vaginalis (frothy, yellow-green)
B) Gardnerella vaginalis (thin gray, fishy odor)
C) Candida albicans ✓
D) Chlamydia trachomatis

Answer: Candida albicans Thick, white, cottage-cheese (curd-like) vaginal discharge is the hallmark of vulvovaginal candidiasis caused by Candida albicans. Other features: intense vulvar pruritus, burning, erythema, satellite lesions. Predisposing factors: diabetes, antibiotics, pregnancy, immunosuppression, oral contraceptives. Diagnosis: KOH wet mount showing pseudohyphae and budding yeast. Treatment: topical azoles (clotrimazole) or oral fluconazole.

Q28. A patient with tetanus (Clostridium tetani infection) - which investigation should be carried out?

A) Blood culture
B) Wound swab (wound culture) ✓
C) CSF culture
D) Stool culture

Answer: Wound swab Tetanus is a clinical diagnosis based on symptoms (trismus, risus sardonicus, opisthotonus, spasms). C. tetani is rarely isolated from blood. The investigation is wound swab/culture from the portal of entry to identify C. tetani (gram-positive, spore-forming, anaerobic bacillus). However, clinical diagnosis is primary - negative culture does NOT exclude tetanus. Serum tetanus antitoxin levels can be measured. Note: the organism produces tetanospasmin (blocks inhibitory neurotransmitter release → spastic paralysis).

Q29. A patient with increased oral pigmentation, hyponatremia, hyperkalemia, and elevated ACTH is diagnosed with adrenal insufficiency. Which condition matches?

A) Primary adrenal insufficiency (Addison's disease) ✓
B) Waterhouse-Friderichsen (acute adrenal crisis from meningococcemia)
C) Secondary adrenal insufficiency (low ACTH)

Answer: Primary adrenal insufficiency (Addison's Disease) The combination of:

Increased ACTH (elevated due to loss of negative feedback from cortisol)
Hyponatremia + Hyperkalemia (loss of aldosterone effect)
Oral mucosal hyperpigmentation (excess ACTH → melanocyte stimulation via POMC)

= Primary adrenal insufficiency (Addison's disease). In secondary/tertiary adrenal insufficiency, ACTH is LOW and mineralocorticoid axis is usually preserved (no hyperkalemia). Waterhouse-Friderichsen is acute bilateral adrenal hemorrhage (N. meningitidis) causing acute adrenal crisis.

Q30. A woman with anovulatory infertility is treated with clomiphene citrate. What is the mechanism of action?

A) Inhibit FSH release
B) Inhibit/block estrogen receptors (anti-estrogen) ✓
C) Downregulate GnRH

Answer: Blocks estrogen receptors in hypothalamus (anti-estrogen) Clomiphene is a selective estrogen receptor modulator (SERM) that acts as an estrogen antagonist at hypothalamic receptors. By blocking estrogen receptors, clomiphene prevents the normal negative feedback of estrogen → hypothalamus/pituitary interpret low estrogen → increase GnRH pulses → increase FSH and LH release → stimulate follicular development and ovulation. So clomiphene increases FSH (does not inhibit it) and upregulates GnRH signaling. The listed answer "inhibit estrogen receptor synthesis" is close - the exact MOA is competitive blockade of hypothalamic estrogen receptors.

Q31. A patient with elevated T3/T4 and decreased TSH is diagnosed with Graves' disease. What is the characteristic microscopic appearance of the thyroid?

A) Flat epithelium, colloid-filled follicles
B) Scalloped colloid with tall follicular epithelium ✓
C) Psammoma bodies
D) Lymphocytic infiltrate only

Answer: Scalloped colloid (Scalloping) In Graves' disease (diffuse toxic goiter), the histology shows:

Tall columnar follicular epithelium (hyperplastic)
Scalloped/moth-eaten edges of colloid (resorption lacunae) - TSH-receptor antibodies stimulate excess thyroid hormone production and colloid reabsorption
Papillary infoldings into follicular lumen
Increased vascularity
Lymphocytic infiltrate (autoimmune)

"Scalloping" refers to the irregular, resorbed edges of the colloid material at the periphery of follicles - a hallmark of hyperstimulated, hyperactive thyroid tissue.

Q32. In the early stage of HIV infection, which protein is associated with the virus?

A) gp120
B) p17 (Protein 17) ✓
C) Reverse transcriptase
D) Integrase

Answer: Protein 17 (p17) HIV structural proteins:

p17: Matrix protein (MA) - lies beneath the lipid envelope, involved in viral assembly and budding. Detected in early HIV infection.
p24: Capsid protein - marker of early HIV infection (p24 antigen test)
gp120: Envelope glycoprotein - binds CD4 and CCR5/CXCR4
gp41: Transmembrane glycoprotein - mediates membrane fusion

In early (acute) HIV, p24 antigenemia is the classic early marker. p17 is the matrix protein. Both are expressed early. The 4th generation HIV test detects both p24 antigen and HIV antibodies.

Q33. A 56-year-old schizophrenic patient on haloperidol develops tardive dyskinesia. The psychiatrist switches to clozapine. Which pharmacological property of clozapine explains this change?

A) Low affinity for dopamine D2 receptors ✓
B) Greater antagonism at muscarinic receptors
C) Blocks dopamine release
D) Activates GABA receptors

Answer: Low affinity for D2 receptors Tardive dyskinesia (TD) is caused by D2 receptor supersensitivity in the nigrostriatal pathway due to chronic D2 blockade by typical antipsychotics (haloperidol). Clozapine is an atypical antipsychotic that has:

Low affinity for D2 receptors (especially in the striatum) → lower risk of extrapyramidal side effects and TD
Loose binding/rapid dissociation from D2 receptors ("hit and run" hypothesis)
Higher affinity for D4, 5-HT2A, H1, M1, alpha-1 receptors

This low D2 striatal occupancy explains why clozapine has the lowest risk of tardive dyskinesia among antipsychotics. Clozapine is the treatment of choice for TD.

Q34. How does HPV cause genital warts?

A) HPV infects basal keratinocytes and spreads upward
B) HPV infects the surface layer of epithelium ✓ (as listed)
C) HPV integrates into the genome causing immediate transformation
D) HPV directly infects immune cells

Answer: HPV infects the surface/epithelial layer HPV infects keratinocytes of the squamous epithelium. The virus enters through micro-abrasions, infects basal keratinocytes (where the actual integration/replication occurs), but the productive infection and viral particle assembly occurs in the upper/surface layers of the epithelium as cells differentiate. In genital warts (condylomata acuminata), HPV types 6 and 11 (low-risk) cause benign papillomatous proliferation. The histological hallmark is koilocytes (perinuclear halo in superficial epithelial cells).

Q35. A malnourished 2-year-old (initial weight 4.75 kg) gains 32% more weight (final weight 6.28 kg) after a nutritional program. Which is the most accurate direct nutritional status assessment method?

A) Clinical examination
B) Biochemical examination
C) Anthropometry ✓
D) Vital statistics

Answer: Anthropometry Anthropometry is the direct, objective measurement of body dimensions to assess nutritional status. It includes:

Weight for age (underweight)
Height/length for age (stunting - chronic malnutrition)
Weight for height (wasting - acute malnutrition)
Mid-upper arm circumference (MUAC)
BMI for age

The question itself demonstrates anthropometric measurement (weight gain monitoring). It is the most accurate direct method because it quantifies physical growth. Biochemical tests (albumin, prealbumin) are indirect. Clinical examination is subjective. Vital statistics are population-level data.

Q36. A patient with dysentery (bloody diarrhea) has pear-shaped organisms found in stool. What is the causative agent?

A) Giardia lamblia (but causes watery diarrhea, NOT dysentery)
B) Entamoeba histolytica ✓ (causes dysentery)
C) Entamoeba coli (non-pathogenic)
D) Balantidium coli

Answer: Entamoeba histolytica (for dysentery) This is a tricky question. Giardia lamblia has a pear/teardrop shape with bilateral symmetry (two nuclei, "owl face"), but causes watery, frothy, non-bloody diarrhea (malabsorptive). Entamoeba histolytica causes amoebic dysentery (bloody mucoid stools, "flask-shaped" ulcers in colon). Since the question specifies "dysentery" (bloody), E. histolytica is the answer, even though Giardia is pear-shaped. E. histolytica trophozoites contain ingested RBCs.

Q37. A patient with obstructive uropathy has a narrow right ureter with scarring, hydronephrosis, and polyuria. What is the pathophysiological consequence?

A) Decreased renin production
B) Decreased glomerular filtration rate (GFR) ✓
C) Increased ADH secretion
D) Metabolic alkalosis

Answer: Decrease in GFR Obstructive uropathy → back pressure in the collecting system → transmitted to Bowman's capsule → reduces the net filtration pressure → decreased GFR. Hydronephrosis develops from urine accumulation proximal to the obstruction. Despite obstruction, paradoxical polyuria can occur due to tubular dysfunction (loss of concentrating ability, nephrogenic diabetes insipidus-like picture). Chronic obstruction leads to renal atrophy and progressive CKD.

Q38. A patient with jaundice and elevated IgM is diagnosed with Hepatitis E. What mechanism explains the jaundice?

A) Autoimmune destruction
B) Complement activation ✓
C) Direct viral hepatocyte lysis
D) Biliary obstruction

Answer: Complement activation (immune-mediated hepatocyte damage) In Hepatitis E (HEV) infection, jaundice results from hepatocyte damage primarily through immune-mediated mechanisms. Elevated IgM indicates acute infection. The immune response involving complement activation, cytotoxic T lymphocytes, and NK cells destroys infected hepatocytes → release of conjugated and unconjugated bilirubin → jaundice. HEV is a fecal-oral RNA virus (Hepeviridae) causing acute hepatitis, particularly severe in pregnant women (fulminant hepatitis, high mortality in 3rd trimester).

Q39. Peutz-Jeghers syndrome involves polyps with a mutation in STK11 (LKB1). What is the histological description of these polyps?

A) Tubular adenoma
B) Superficial columnar epithelium with goblet cells over arborizing smooth muscle ✓
C) Villous adenoma
D) Inflammatory polyps

Answer: Hamartomatous polyps with columnar and goblet cells Peutz-Jeghers polyps are hamartomas characterized by:

Arborizing smooth muscle core (from muscularis mucosae)
Covered by normal intestinal epithelium - columnar cells with goblet cells
Non-dysplastic (benign hamartoma)
STK11/LKB1 mutation (tumor suppressor)
Associated with: mucocutaneous pigmentation (lips, buccal mucosa), GI polyps, increased risk of GI and extra-GI cancers

Q40. A diffuse infiltrative malignant neoplasm of the stomach is best described as:

A) Squamous cell carcinoma
B) Carcinoid tumor
C) Adenocarcinoma (linitis plastica/diffuse type) ✓
D) Lymphoma

Answer: Adenocarcinoma (diffuse/infiltrative type) Diffuse-type gastric adenocarcinoma (Lauren classification) is characterized by:

Diffuse infiltration of the stomach wall without a discrete mass
Signet ring cells (intracellular mucin displacing nucleus)
Linitis plastica ("leather bottle stomach") - diffuse fibrotic thickening
Poor prognosis, no gland formation
Associated with CDH1 (E-cadherin) mutation, blood group A, young women
Contrast with intestinal-type: forms glands, associated with H. pylori, elderly males

Q41. A patient with rabies has rapid spread to the CNS. What mechanism accounts for this?

A) Hematogenous spread
B) Direct lymphatic spread
C) Migration of infected epidermal dendritic cells ✓ (as listed, though mechanism below)
D) CSF dissemination

Answer: Retrograde axonal transport The actual mechanism of rabies CNS spread is retrograde axonal transport - rabies virus binds to nicotinic ACh receptors and neural cell adhesion molecules at the neuromuscular junction → enters motor neurons → travels centripetally up axons via retrograde fast axonal transport at ~50-100mm/day toward the CNS. The listed answer mentions "migration of infected epidermal dendritic cells" - this may refer to initial viral uptake. The classic accepted mechanism is retrograde axonal transport via peripheral nerves to the spinal cord and brain.

Q42. What is the infective stage of Fasciola hepatica (liver fluke)?

A) Miracidium
B) Sporocyst
C) Redia
D) Metacercaria ✓ (NOT Cercaria)

Answer: Metacercaria (not Cercaria) The life cycle of Fasciola hepatica:

Eggs → miracidium → sporocyst → redia → cercaria (free-swimming, exits snail) → metacercaria (encysts on aquatic vegetation, e.g., watercress)
Metacercaria = INFECTIVE STAGE for humans (ingested on water plants)
Metacercaria → excyst in duodenum → juvenile flukes → penetrate intestinal wall → peritoneum → liver capsule → bile ducts

The listed answer "Cercaria" is incorrect. Metacercaria is the infective stage. Cercaria is the free-swimming stage that encysts to become metacercaria.

Q43. A study reports a p-value of 0.4. What does this mean?

A) Statistically significant result
B) Strong evidence against the null hypothesis
C) Fail to reject the null hypothesis (not statistically significant) ✓
D) 40% chance the alternative hypothesis is true

Answer: Not statistically significant - fail to reject null hypothesis A p-value of 0.4 (40%) means: if the null hypothesis were true, there is a 40% probability of observing results as extreme as those found by chance alone. Since p = 0.4 > alpha (0.05), we fail to reject the null hypothesis. The result is not statistically significant. It does NOT mean the null hypothesis is true, nor that there is no effect - only that the evidence is insufficient to reject it. (A p-value < 0.05 would be considered statistically significant.)

Q44. A patient has increased extracellular fluid, increased vascular permeability, and edema affecting the interstitial/extracellular space of the brain. What type of edema is this?

A) Cytotoxic edema (intracellular, cell swelling)
B) Interstitial edema (transependymal)
C) Osmotic edema
D) Vasogenic edema ✓

Answer: Vasogenic edema Vasogenic edema is caused by increased blood-brain barrier (BBB) permeability → plasma proteins and fluid leak into the extracellular space (interstitium) of the brain. Causes: brain tumors, abscesses, trauma, hemorrhage, meningitis. Features:

Affects white matter more than gray matter (white matter has more extracellular space)
Increased permeability to plasma proteins (albumin)
Responds to corticosteroids (dexamethasone)

Contrast with cytotoxic edema (intracellular swelling from Na+/K+ ATPase failure, e.g., ischemia) - does NOT respond to steroids.

Q45. Entamoeba histolytica cysts in the intestine - what is the treatment to eradicate cysts?

A) Chloroquine (for hepatic amoebiasis)
B) Metronidazole ✓ (systemic) + Diloxanide furoate or Paromomycin (luminal)
C) Albendazole
D) Quinine

Answer: Metronidazole (+ luminal agent) Treatment of amoebiasis:

Metronidazole (nitroimidazole): kills tissue trophozoites - effective for invasive intestinal and hepatic amoebiasis
Luminal agents (diloxanide furoate, paromomycin, iodoquinol): kill intestinal cysts and non-invasive trophozoites

Complete eradication requires BOTH: metronidazole first → then a luminal agent to clear cysts (to prevent relapse and transmission). Metronidazole alone has poor luminal efficacy. The listed answer metronidazole is correct as the primary drug.

Q46. Why does maternal mortality rate serve as an indicator of health system development?

A) Only measures death during labor
B) Reflects nutrition status
C) Maternal death is irrespective of duration and site of pregnancy ✓
D) Correlates with infant mortality only

Answer: Maternal death is irrespective of duration/site of pregnancy The maternal mortality ratio (MMR) is a sensitive indicator of health system quality because maternal deaths:

Reflect the quality of antenatal care, skilled birth attendance, emergency obstetric care, and postnatal care
Are largely preventable with adequate healthcare
Span all stages of pregnancy and puerperium (regardless of duration or site)
Require a functional healthcare system at all levels (primary to tertiary)
Correlate with poverty, healthcare access, gender equity, and education

The WHO defines maternal death as "death of a woman while pregnant or within 42 days of termination of pregnancy, irrespective of duration and site of pregnancy, from any cause related to or aggravated by the pregnancy or its management."

Q47. A patient presents with hematuria and a solitary nodular renal mass. Histology shows clusters of pleomorphic malignant cells with clear cytoplasm. What is the diagnosis?

A) Wilms' tumor (nephroblastoma - in children)
B) Transitional cell carcinoma (papillary, urothelial)
C) Oncocytoma (benign, uniform cells)
D) Clear cell renal carcinoma (Clear cell RCC) ✓

Answer: Clear cell renal carcinoma Clear cell carcinoma of the kidney (most common type of renal cell carcinoma, ~70-75%) is characterized by:

Large cells with clear/pale cytoplasm (rich in glycogen and lipid, washed out in H&E processing)
Pleomorphic nuclei
Prominent vascularity
Arising from proximal tubular epithelium
Associated with VHL gene mutation (chromosome 3p deletion)
Classic triad: hematuria, flank pain, palpable mass ("too late" triad)
May present with paraneoplastic syndromes

Q48. The epidemiological triad is the traditional model of infectious disease causation. Which combination represents its components?

A) Primary, secondary, tertiary prevention
B) Time, place, person
C) Source, mode of transmission, susceptible host
D) Agent, Host, Environment ✓

Answer: Agent, Host, Environment The epidemiological triad (traditional model of infectious disease) consists of three components:

Agent: the causative organism (bacteria, virus, parasite, fungi)
Host: the susceptible individual (age, immunity, genetics, behavior)
Environment: external factors facilitating transmission (climate, sanitation, vectors, social conditions)

Disease occurs when the balance between these three is disrupted. This model is also called the "epidemiological triangle." Time, place, person = descriptive epidemiology. Source-transmission-host = chain of infection.

Q49. A patient with fixed, short breathe (dyspnea), blood dyscrasias, and dysentery is treated with sulfamethoxazole. What complication develops?

A) Methemoglobinemia
B) Sulfonamide-induced hemolytic anemia ✓
C) Agranulocytosis
D) Aplastic anemia

Answer: Sulfonamide drug-induced hemolytic anemia Sulfonamides (sulfamethoxazole) can cause hemolytic anemia, particularly in patients with G6PD deficiency (glucose-6-phosphate dehydrogenase deficiency) where RBCs cannot withstand oxidative stress. Sulfonamides are oxidant drugs → oxidative hemolysis in G6PD-deficient RBCs. Other sulfonamide adverse effects: crystalluria, Stevens-Johnson syndrome, kernicterus (neonates), hypersensitivity, folate antagonism. "Sulphur drug-induced anemia" = hemolytic anemia.

Q50. Schistosoma haematobium (urinary schistosomiasis) - what investigation is diagnostic?

A) Stool microscopy
B) Rectal biopsy
C) Urine microscopy (urine examination for ova) ✓
D) Serology alone

Answer: Urine examination Schistosoma haematobium uniquely infects the urinary venous plexus (vesical plexus), causing urogenital schistosomiasis - hematuria, dysuria, bladder granulomas, and increased risk of bladder squamous cell carcinoma. Diagnosis: urine microscopy for ova - the characteristic terminal-spined eggs in the urine (especially in midday urine). Contrast with S. mansoni and S. japonicum (intestinal) - stool microscopy. Treatment: praziquantel (drug of choice for all schistosomiasis).

Q51. A patient has CNS demyelination, leg weakness, and oligoclonal bands in CSF. What is the cause?

A) Autoimmune demyelination (Multiple Sclerosis) ✓
B) Abrupt withdrawal of drugs
C) Viral encephalitis
D) Vitamin B12 deficiency

Answer: Autoimmune demyelination (Multiple Sclerosis) The triad of:

CNS demyelination (MRI: periventricular white matter plaques)
Leg weakness (motor deficits)
Oligoclonal bands in CSF (IgG bands from intrathecal immunoglobulin synthesis)

= Multiple Sclerosis (MS) - an autoimmune demyelinating disease mediated by autoreactive T cells against myelin antigens (MBP, MOG, PLP). Oligoclonal bands (present in >90% of MS cases) represent intrathecal antibody production. Treatment: interferons, glatiramer, natalizumab, dimethyl fumarate.

Q52. SLE is treated with corticosteroids. Abrupt withdrawal leads to rebound hypertension. Why?

A) Psychologic dependence
B) Hyperglycemia
C) Acute adrenal insufficiency ✓
D) Somatotropin (GH) excess

Answer: Acute adrenal insufficiency Long-term corticosteroid therapy causes HPA (hypothalamic-pituitary-adrenal) axis suppression. Exogenous steroids feedback to suppress CRH (hypothalamus) and ACTH (pituitary) → adrenal cortex atrophies from disuse. Abrupt withdrawal → adrenal glands cannot produce adequate cortisol → acute adrenal insufficiency (adrenal crisis): hypotension (not hypertension), weakness, nausea, vomiting, hyponatremia, hyperkalemia. The question states "rebound hypertension" which is atypical - withdrawal usually causes hypotension. The mechanism is acute adrenal insufficiency.

Q53. A 3-year-old girl with short stature and loose neck skin (webbed neck) has XO karyotype (Turner syndrome). Which drug best achieves appropriate height?

A) GHRH
B) Adrenocorticotropin (ACTH)
C) CRH
D) Recombinant Growth Hormone (GH) ✓

Answer: Growth Hormone (Recombinant GH / Somatropin) Turner syndrome (45,XO) presents with: short stature, webbed neck, shield chest, wide-carrying angle, ovarian dysgenesis, horseshoe kidney, coarctation of aorta. Treatment for short stature: recombinant human growth hormone (somatropin), started early (before age 9-12). GH therapy increases final adult height by 5-8 cm. GHRH is a hypothalamic hormone that stimulates GH release - not used therapeutically for Turner's. The answer is growth hormone (GH/somatropin), which was not listed among the options - among the listed options, GHRH is closest as it stimulates GH release, but direct GH replacement is the actual treatment.

Q54. Campylobacter jejuni's virulence factor that causes intestinal inflammation is:

A) Flagella
B) Adhesins ✓
C) Lipopolysaccharide
D) Exotoxins

Answer: Adhesins Campylobacter jejuni causes inflammation through multiple virulence factors:

Adhesins (CadF, FlpA, JlpA): mediate attachment to intestinal epithelial cells - initiating the inflammatory cascade
Flagella: motility and colonization, also suppress innate immunity
Cytolethal distending toxin (CDT): DNA damage, apoptosis
LPS/LOS: inflammatory response, molecular mimicry (Guillain-Barre syndrome)

Adhesins are the initial step - without adhesion, C. jejuni cannot colonize and cause disease.

Q55. A Type 1 diabetic patient uses insulin injections. He is advised to avoid injecting in the same site repeatedly. Why?

A) Risk of infection
B) Variable insulin absorption
C) Lipodystrophy ✓
D) Nerve damage

Answer: Lipodystrophy Repeated insulin injection at the same site causes lipohypertrophy (most common) - a benign, rubbery, subcutaneous fat accumulation from insulin's lipogenic effect on adipocytes. Less commonly, lipoatrophy (fat atrophy) occurs. Lipohypertrophy is painless but causes erratic, unpredictable insulin absorption from that site → poor glycemic control. Prevention: rotate injection sites systematically (abdomen, thigh, buttock, upper arm). This combined issue of lipohypertrophy + lipoatrophy = lipodystrophy.

Q56. A patient with insomnia and anxiety needs a drug that increases the inhibitory effect of GABA on neuronal excitability. Which drug is appropriate and what is its mechanism?

Answer: Benzodiazepine

Mechanism: Benzodiazepines bind to the GABA-A receptor at the benzodiazepine site (between alpha and gamma subunits), increasing the FREQUENCY of chloride ion channel opening (not amplitude). This increases Cl- influx into the neuron → hyperpolarization → membrane becomes more negative → neuron is less excitable → inhibitory effect (anxiolytic, sedative, anticonvulsant, muscle relaxant). Used for insomnia and anxiety disorders. Risk: tolerance, dependence, withdrawal.

Q57. A patient with hypopituitarism from a non-functional pituitary adenoma - which endocrine axis is affected FIRST?

A) Breast (prolactin - actually increases with stalk compression)
B) Gonadal axis (FSH/LH → ovaries) - but listed as "Ovary" ✓
C) Thyroid (TSH)
D) Adrenal cortex (ACTH)

Answer: The order of pituitary hormone loss in hypopituitarism Classic sequence of hormone loss due to pituitary compression:

GH (first lost - growth hormone)
FSH/LH (gonadotropins - ovarian/testicular function, menstrual irregularity)
TSH (thyroid)
ACTH (adrenal - last lost, most dangerous if absent)
Prolactin (may actually increase if stalk compressed)

Among the listed options (Breast/prolactin, Ovary/FSH-LH, Thyroid/TSH, Cortex/ACTH), Ovary (gonadotropins/FSH-LH) is lost relatively early (2nd after GH). The adrenal cortex (ACTH) is typically the last to fail.

Q58. A patient has sensorineural hearing loss and a well-circumscribed tumor at the cerebellopontine angle. Microscopy shows Antoni A and B patterns with Verocay bodies. Which cells are affected?

A) Oligodendrocytes
B) Astrocytes
C) Ependymal cells
D) Schwann cells ✓

Answer: Schwann cells (Acoustic Neuroma / Vestibular Schwannoma) This is a classic description of vestibular schwannoma (acoustic neuroma):

Location: cerebellopontine angle (CN VIII)
Symptoms: progressive sensorineural hearing loss, tinnitus, vertigo
Histology: Antoni A (compact spindle cells in palisading pattern) + Antoni B (loose myxoid areas) + Verocay bodies (nuclear palisading around acellular zones)
Cells of origin: Schwann cells of the vestibular branch of CN VIII
Associated with NF2 (bilateral acoustic neuromas = NF2 diagnostic)

Q59. A patient with Cryptococcus neoformans meningitis is treated with Amphotericin B + Flucytosine (5-FC). Why use combination therapy?

A) Reduce cost
B) Cover additional organisms
C) Prevent development of antifungal resistance ✓
D) Reduce dosing frequency

Answer: Prevent resistance (and synergistic effect) The combination of Amphotericin B + Flucytosine (5-FC) for cryptococcal meningitis is the induction regimen (WHO/IDSA guidelines). The rationale:

Synergy: Amphotericin B damages the fungal cell membrane → increases intracellular penetration of 5-FC → 5-FC is converted to 5-fluorouracil → inhibits DNA/RNA synthesis
Prevent resistance: Using 5-FC alone rapidly selects resistant mutants (mutations in cytosine deaminase/permease). Combination prevents this.
Faster CSF sterilization compared to monotherapy

After 2 weeks induction → consolidation with fluconazole → maintenance fluconazole.

Q60. A patient with painful genital ulcers is diagnosed with chancroid. What is the diagnostic test?

A) Dark-field microscopy (syphilis)
B) Tzanck smear (HSV)
C) Nucleic acid amplification test (NAAT)/Nucleic acid probe for Haemophilus ducreyi ✓
D) VDRL

Answer: Nucleic acid probe/NAAT for Haemophilus ducreyi Chancroid is caused by Haemophilus ducreyi - a gram-negative coccobacillus. It presents with: painful genital ulcers (soft, undermined edges), unilateral tender inguinal lymphadenopathy (bubo). Diagnosis:

Gold standard: Culture on selective media (difficult, <80% sensitivity)
NAAT/Nucleic acid probe: PCR-based, high sensitivity and specificity, detects H. ducreyi DNA
Gram stain: "school of fish" pattern (gram-negative coccobacilli)
Clinical diagnosis often made by exclusion (HSV-negative, syphilis-negative + compatible presentation)

Treatment: Azithromycin 1g single dose or ceftriaxone 250mg IM.

Summary Table

Q	Key Answer	Core Concept
1	Intestinal obstruction	Taenia adult worm, mechanical blockage
2	Parathyroid adenoma (benign)	Primary hyperparathyroidism triad
3	Mononuclear cell infiltrate at SCJ	Chronic cervicitis histology
4	Mature cystic teratoma	Skin/hair/teeth = dermoid cyst
5	Acid-fast slit-skin smear	Leprosy diagnosis
6	Hypocalcemia	Steroid-induced calcium loss
7	PRNP gene mutation	Prion disease mechanism
8	Case-control	Backward/retrospective study design
9	Jaundice NOT typical	Uncomplicated acute cholecystitis
10	MMR (live vaccine)	Contraindicated in immunocompromised
11	Gastric acid	GERD-related reflux esophagitis
12	Nystagmus	Phenytoin toxicity
13	WBC cast	Acute pyelonephritis
14	Mask visceral pain	Opioid in acute abdomen
15	Proteus sp.	Urease+, swarming, alkaline urine
16	Atherosclerosis	Diabetes + dyslipidemia = MCA stroke
17	Circulatory disease	Leading cause of death in Malaysia
18	Choriocarcinoma	Post-menopausal bleeding, no mass
19	Thrombotic microangiopathy	Drug-induced nephrotoxicity
20	Previous C-section	Oxytocin + uterine scar = rupture risk
21	Collecting duct	Spironolactone MOA (aldosterone antagonist)
22	Subepithelial immune deposits	Membranous nephropathy ("spikes")
23	DEC (not praziquantel)	Filariasis treatment
24	Trastuzumab (not tamoxifen)	HER2+ breast cancer
25	Testicular torsion	Adolescent acute scrotal pain
26	Ability to cause clinical disease	Definition of virulence
27	Candida albicans	Cottage-cheese discharge
28	Wound swab	Tetanus investigation
29	Primary adrenal insufficiency	High ACTH + pigmentation + electrolyte imbalance
30	Block estrogen receptors	Clomiphene MOA
31	Scalloped colloid	Graves' disease histology
32	p17 protein	Early HIV marker
33	Low D2 affinity	Clozapine vs. tardive dyskinesia
34	Infects epithelial surface layer	HPV wart mechanism
35	Anthropometry	Direct nutritional assessment
36	E. histolytica (dysentery)	Giardia = pear shape but watery diarrhea
37	Decreased GFR	Obstructive uropathy physiology
38	Complement activation	Hepatitis E jaundice mechanism
39	Columnar + goblet cells (hamartoma)	Peutz-Jeghers polyp histology
40	Adenocarcinoma (linitis plastica)	Diffuse gastric carcinoma
41	Retrograde axonal transport	Rabies CNS spread
42	Metacercaria (not cercaria)	Fasciola infective stage
43	Not significant (p > 0.05)	p-value 0.4 interpretation
44	Vasogenic edema	BBB breakdown, extracellular edema
45	Metronidazole + luminal agent	Amoeba cyst eradication
46	Death irrespective of pregnancy duration	Why MMR = health system indicator
47	Clear cell renal carcinoma	Clear cytoplasm, hematuria, renal mass
48	Agent, Host, Environment	Epidemiological triad
49	Hemolytic anemia (G6PD)	Sulfonamide side effect
50	Urine microscopy	Schistosoma haematobium diagnosis
51	Autoimmune demyelination (MS)	Oligoclonal bands + demyelination
52	Acute adrenal insufficiency	Steroid withdrawal HPA suppression
53	Growth hormone	Turner syndrome treatment
54	Adhesins	Campylobacter virulence
55	Lipodystrophy	Repeated insulin injection site
56	Benzodiazepine - Cl- influx	GABA-A receptor, anxiolytic
57	Ovary (FSH/LH) - early loss	Hypopituitarism sequence
58	Schwann cells	Vestibular schwannoma histology
59	Prevent resistance + synergy	Ampho B + 5-FC for Cryptococcus
60	NAAT/nucleic acid probe	Chancroid (H. ducreyi) diagnosis

Notes on discrepancies in listed answers:

Q23: Praziquantel is for trematodes/cestodes; DEC is correct for filariasis
Q24: Tamoxifen is for ER+ cancer; Trastuzumab is correct for HER2+
Q42: Cercaria is listed but Metacercaria is the true infective stage of Fasciola

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