Make MCQ on measles Chickenpox Dermatophytosis Candidiasis Case scenario based mcqs

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Case Scenario-Based MCQs

MEASLES (5 MCQs)

Q1. A 4-year-old unvaccinated boy presents with 3 days of high fever, cough, coryza, and conjunctivitis. On examination, 1–2 mm white spots on an erythematous base are seen on the buccal mucosa opposite the lower molars. Two days later, a maculopapular rash appears behind the ears and spreads downward. Which of the following best describes the pathognomonic finding in this case?

A) Nikolsky sign
B) Koplik's spots
C) Rose spots
D) Pastia's lines

Answer: B - Koplik's spots Explanation: Koplik's spots are pathognomonic for measles - white spots on an erythematous buccal mucosa, classically opposite the lower molars, appearing 2 days before the exanthem. The 3 Cs (cough, coryza, conjunctivitis) constitute the classic measles prodrome. - Harrison's Principles of Internal Medicine 22E

Q2. The same boy's mother asks how long he was infectious. She heard that her child could have spread the disease to others even before the rash appeared. What is the correct infectious period for measles?

A) Only from the day of rash onset until 4 days after
B) From 4 days before rash through 4 days after rash onset
C) From the first day of fever through 10 days after
D) Only when cough is present

Answer: B - From 4 days before rash through 4 days after rash onset Explanation: Measles patients are infectious from 4 days before rash appearance to 4 days after. Immunocompromised patients may remain contagious for the entire duration of illness due to prolonged viral shedding. - Red Book 2021

Q3. A 6-year-old child with measles develops progressive confusion, seizures, and personality changes 10 years later. MRI shows diffuse cortical atrophy. CSF reveals elevated IgG antibodies to measles virus. What is the most likely diagnosis?

A) Viral encephalitis
B) Subacute Sclerosing Panencephalitis (SSPE)
C) Multiple sclerosis
D) Progressive multifocal leukoencephalopathy

Answer: B - Subacute Sclerosing Panencephalitis (SSPE) Explanation: SSPE is a rare, fatal, chronic encephalitis caused by persistent measles virus infection of the CNS. The mean incubation period is ~10.8 years after the original infection. These patients are NOT contagious. High CSF measles IgG antibodies and characteristic EEG changes (Radermecker complexes) are diagnostic. - Red Book 2021

Q4. A 9-year-old malnourished child in a refugee camp presents with measles and develops progressive respiratory distress. Chest X-ray shows bilateral infiltrates. Which complication is she most likely experiencing?

A) Bacterial pneumonia only
B) Pleural effusion from measles pleuritis
C) Giant cell pneumonitis due to measles virus replication in the lungs
D) Pulmonary tuberculosis reactivation

Answer: C - Giant cell pneumonitis due to measles virus replication in the lungs Explanation: Most measles complications involve the respiratory tract. In immunocompromised or malnourished persons, giant cell pneumonitis can develop from direct measles virus replication in lung tissue. Acute laryngotracheobronchitis (croup) is also a recognized complication. Secondary bacterial infections are common as well. - Harrison's Principles of Internal Medicine 22E

Q5. A mother brings her 14-month-old for MMR vaccination. She reports the child received one dose at 12 months. You advise her that a 2-dose schedule is needed. What is the primary reason for the 2-dose MMR recommendation?

A) The second dose boosts against mumps only
B) Primary vaccine failure occurs in up to 7% after a single dose
C) The first dose protects for only 5 years
D) Waning immunity is the major cause of all breakthrough cases

Answer: B - Primary vaccine failure occurs in up to 7% after a single dose Explanation: Inadequate response (primary vaccine failure) occurs in up to 7% of recipients of a single dose given at 12 months or older. The 2-dose schedule was introduced primarily to address these primary vaccine failures, not waning immunity (secondary vaccine failure), which accounts for a minority of breakthrough cases. - Red Book 2021

CHICKENPOX / VARICELLA (5 MCQs)

Q6. A 7-year-old girl presents with a 2-day history of fever followed by a pruritic rash. On examination, you find lesions in various stages: macules, papules, vesicles, and crusts - all present simultaneously on the trunk, face, and scalp. What is the most likely diagnosis and the classic description of this rash pattern?

A) Smallpox - uniform lesions in the same stage
B) Chickenpox - lesions in multiple stages ("dewdrops on a rose petal")
C) Impetigo - honey-crusted lesions
D) Hand-foot-and-mouth disease - oval vesicles on palms and soles

Answer: B - Chickenpox - lesions in multiple stages ("dewdrops on a rose petal") Explanation: Varicella is characterized by lesions in multiple simultaneous stages (pleomorphic), described as "dewdrops on a rose petal" - a thin-walled vesicle on an erythematous base. Unlike smallpox, where all lesions are in the same stage (monomorphic) and are more peripheral in distribution. - Harrison's Principles of Internal Medicine 22E

Q7. A 32-year-old pregnant woman (26 weeks) develops varicella. She has no prior immunity. Besides fetal risk, which pulmonary complication must you be vigilant for in this adult patient?

A) Asthma exacerbation
B) Varicella pneumonia - occurs more commonly and severely in adults
C) Pulmonary edema from myocarditis
D) Pneumothorax from coughing

Answer: B - Varicella pneumonia - occurs more commonly and severely in adults Explanation: Although varicella is generally benign in healthy children, pneumonia is the most serious complication in adults. Varicella pneumonia is characterized by interstitial pneumonitis, multinucleated giant cells, intranuclear inclusions, and pulmonary hemorrhage. Pregnant women are at particularly high risk for severe pneumonia. - Harrison's/Grainger & Allison's Diagnostic Radiology

Q8. A 45-year-old man is admitted with painful unilateral vesicular eruption in a dermatomal distribution on his chest, without crossing the midline. He had chickenpox as a child. Which of the following best explains the pathophysiology of his current condition?

A) Re-infection with a new varicella-zoster virus strain
B) Reactivation of latent VZV from dorsal root ganglia
C) Spread of VZV through blood from a skin wound
D) Cross-reaction with herpes simplex virus type 2

Answer: B - Reactivation of latent VZV from dorsal root ganglia Explanation: During primary varicella infection, VZV establishes latency in sensory (dorsal root, cranial, and enteric) ganglia. Reactivation later in life, especially after age 60 or in immunocompromised states, causes herpes zoster (shingles) - a unilateral, dermatomal, painful vesicular eruption. - Harrison's Principles of Internal Medicine 22E

Q9. A neonate is born to a mother who developed chickenpox 2 days before delivery. The pediatrician is concerned about severe neonatal varicella. Which prophylaxis is indicated?

A) Oral acyclovir for 7 days
B) VariZIG (varicella-zoster immune globulin) administration
C) Immediate MMR vaccination
D) No intervention needed as maternal antibodies protect the newborn

Answer: B - VariZIG (varicella-zoster immune globulin) administration Explanation: Newborns are at high risk for severe varicella when the mother develops chickenpox within 5 days before or 48 hours after delivery (insufficient time for maternal IgG to transfer to the fetus). VariZIG is indicated for these neonates, as well as for immunocompromised susceptible children and susceptible pregnant women with significant exposure. - Harrison's Principles of Internal Medicine 22E

Q10. A 10-year-old with chickenpox is given aspirin for fever by his parents. Three days later, he develops vomiting, confusion, and elevated liver enzymes. What is the most likely diagnosis?

A) Viral hepatitis A co-infection
B) Reye syndrome
C) Varicella encephalitis
D) Drug-induced hepatitis from antivirals

Answer: B - Reye syndrome Explanation: Reye syndrome is a potentially fatal condition characterized by acute non-inflammatory encephalopathy and fatty liver degeneration. It is strongly associated with aspirin use during viral infections, particularly varicella and influenza in children. Aspirin should NEVER be given to children with viral infections for this reason.

DERMATOPHYTOSIS (5 MCQs)

Q11. A 16-year-old wrestler presents with a scaly, annular, erythematous plaque with a raised advancing border on his neck and upper arm. The center shows some clearing. KOH preparation of skin scrapings from the border shows branching hyphae. What is the most likely diagnosis and most common causative organism in this setting?

A) Tinea cruris caused by Epidermophyton floccosum
B) Tinea corporis gladiatorum caused by Trichophyton tonsurans
C) Pityriasis versicolor caused by Malassezia furfur
D) Candida intertrigo

Answer: B - Tinea corporis gladiatorum caused by Trichophyton tonsurans Explanation: "Tinea corporis gladiatorum" is a form of tinea corporis occurring in wrestlers due to skin-to-skin contact, mat burns, and occlusive clothing. T. tonsurans is the most common cause, and the head, neck, and arms are the most frequently affected sites. The classic "ringworm" annular morphology results from host inflammatory response against a spreading dermatophyte. - Fitzpatrick's Dermatology

Q12. A 60-year-old immunosuppressed woman on long-term corticosteroids is referred for scaly, follicular papules and nodules on her lower legs in an annular arrangement. She shaves her legs regularly. Skin biopsy shows fungal hyphae deep within hair follicles. What is the diagnosis?

A) Tinea pedis
B) Tinea incognito
C) Majocchi granuloma
D) Candidal folliculitis

Answer: C - Majocchi granuloma Explanation: Majocchi granuloma is a deep dermatophytic infection involving hair follicles. It presents as scaly, follicular papules/nodules in an annular arrangement. Risk factors include shaving, topical corticosteroid use, and immunosuppression. Most commonly caused by T. rubrum, T. interdigitale, and M. canis. - Fitzpatrick's Dermatology

Q13. A 25-year-old man presents with itchy, scaling, ring-like lesions in the groin, extending to the inner thighs but sparing the scrotum. The rash appears worse in hot, humid weather. His feet also show similar scaling between the toes. What is the most appropriate first-line treatment?

A) Oral fluconazole 150 mg single dose
B) Topical terbinafine or topical azole for 2-4 weeks
C) Topical hydrocortisone cream
D) Oral griseofulvin for 6 months

Answer: B - Topical terbinafine or topical azole for 2-4 weeks Explanation: Tinea cruris (jock itch) is the 2nd most common dermatophytosis worldwide. It often co-exists with tinea pedis (autoinoculation). Sparing of the scrotum differentiates it from candidal intertrigo (which involves the scrotum). Topical antifungals (terbinafine, clotrimazole, miconazole) are first-line. Topical steroids alone worsen tinea (can cause tinea incognito). - Fitzpatrick's Dermatology

Q14. A child is brought in with patchy hair loss on the scalp, with broken-off hair stubs, scaling, and an inflammatory boggy mass that is tender and discharges pus when compressed. What is the name of this severe scalp dermatophytosis and the appropriate management?

A) Tinea capitis without kerion - topical antifungal only
B) Kerion celsi - requires systemic antifungal (oral griseofulvin or terbinafine)
C) Alopecia areata - topical corticosteroids
D) Bacterial scalp abscess - oral antibiotics

Answer: B - Kerion celsi - requires systemic antifungal (oral griseofulvin or terbinafine) Explanation: Kerion is an exaggerated inflammatory host response to scalp dermatophytosis (tinea capitis), forming a boggy, tender, suppurative mass. It requires systemic antifungals - topical agents cannot penetrate the hair shaft. Oral griseofulvin has been the traditional choice; terbinafine is also effective. A short course of systemic steroids may reduce scarring. - Fitzpatrick's Dermatology / Medical Microbiology 9e

Q15. A 70-year-old diabetic man presents with thickened, brittle, discolored (yellow-brown) toenails, with subungual debris. KOH of nail scrapings is positive. What is the most appropriate systemic treatment and duration?

A) Topical clotrimazole cream for 4 weeks
B) Oral terbinafine 250 mg daily for 12 weeks (toenails)
C) Oral fluconazole 200 mg weekly for 4 weeks
D) Topical ciclopirox nail lacquer for 2 weeks

Answer: B - Oral terbinafine 250 mg daily for 12 weeks (toenails) Explanation: Onychomycosis (tinea unguium) requires systemic antifungals. Oral terbinafine 250 mg daily for 12 weeks (toenails) or 6 weeks (fingernails) is the treatment of choice. It has the highest cure rates. Topical agents alone are ineffective for nail plate involvement. Diabetic patients need more vigilant follow-up due to risk of secondary bacterial infections. - Fitzpatrick's Dermatology

CANDIDIASIS (5 MCQs)

Q16. A 35-year-old woman with HIV (CD4 count 80 cells/μL) presents with white, curd-like patches on her tongue and buccal mucosa. The patches can be easily scraped off, leaving an erythematous base. KOH preparation shows budding yeast with pseudohyphae. What is the most likely organism and its distinguishing laboratory feature?

A) Cryptococcus neoformans - India ink positive capsule
B) Candida albicans - germ tube formation in serum at 37°C within 90 minutes
C) Aspergillus fumigatus - septate hyphae with 45-degree branching
D) Histoplasma capsulatum - intracellular yeast in macrophages

Answer: B - Candida albicans - germ tube formation in serum at 37°C within 90 minutes Explanation: Oropharyngeal candidiasis (thrush) is the most common manifestation of Candida infection in HIV/AIDS and correlates with low CD4 counts (deficient T-cell immunity). C. albicans is unique among Candida species in producing germ tubes when incubated in serum for 60-90 minutes at 37°C. It is also the only species producing chlamydospores on nutritionally deficient media. - Jawetz Medical Microbiology 28E / Goldman-Cecil Medicine

Q17. A 55-year-old woman on broad-spectrum antibiotics for pneumonia develops a white, painful tongue coating and vulvovaginal itching with a thick, white, "cottage cheese" discharge. What is the pathophysiological mechanism linking antibiotic use to candidiasis?

A) Antibiotics directly stimulate Candida growth by providing nutrients
B) Antibiotics suppress competing bacterial flora, allowing Candida overgrowth
C) Antibiotics cause immunosuppression and decrease phagocytes
D) Antibiotics cross-react with antifungal pathways

Answer: B - Antibiotics suppress competing bacterial flora, allowing Candida overgrowth Explanation: Broad-spectrum antibacterial antibiotics disrupt the normal bacterial flora of the oral mucosa, gastrointestinal tract, and vaginal mucosa, removing the competitive inhibition that limits Candida colonization. This leads to large increases in the endogenous Candida population and mucosal invasion by yeasts and pseudohyphae. - Jawetz Medical Microbiology 28E

Q18. A 50-year-old ICU patient with a central venous catheter develops fever unresponsive to broad-spectrum antibiotics. Blood cultures grow Candida species. Which of the following is the most important immediate step in management?

A) Add vancomycin to cover Gram-positive organisms
B) Remove the central venous catheter and initiate antifungal therapy
C) Start oral fluconazole and observe
D) Await antifungal sensitivity results before treating

Answer: B - Remove the central venous catheter and initiate antifungal therapy Explanation: Central venous catheters are a major source of nosocomial candidemia, as Candida can contaminate and colonize catheter surfaces. Removal of the catheter is essential, alongside prompt antifungal therapy (echinocandin such as caspofungin/micafungin is first-line for invasive candidiasis). Delay in treatment worsens mortality in candidemia. - Jawetz Medical Microbiology 28E / Washington Manual

Q19. A 28-year-old woman presents with recurrent vulvovaginal candidiasis (4 or more episodes per year). She has no known immunodeficiency. Which of the following is the most appropriate long-term management strategy?

A) Topical nystatin cream applied indefinitely
B) Oral fluconazole 150 mg once weekly for 6 months (suppressive therapy)
C) Boric acid pessaries used only during acute episodes
D) Systemic amphotericin B for 2 weeks

Answer: B - Oral fluconazole 150 mg once weekly for 6 months (suppressive therapy) Explanation: Recurrent vulvovaginal candidiasis (RVVC) is defined as ≥4 symptomatic episodes per year. After induction with daily fluconazole for 3 days, maintenance/suppressive therapy with weekly oral fluconazole for 6 months significantly reduces recurrences. Continuous/intermittent systemic antifungal medications can prevent recurrences but increase the risk of resistant strains. - Dermatology 2-Volume Set 5e

Q20. A 2-year-old child presents with a bright red, sharply demarcated diaper rash with satellite papules and pustules beyond the main rash border. It is not responding to zinc oxide ointment. What is the diagnosis and most appropriate treatment?

A) Irritant contact dermatitis - increase zinc oxide frequency
B) Candidal diaper dermatitis - topical antifungal (nystatin or clotrimazole)
C) Staphylococcal impetigo - topical mupirocin
D) Psoriasis of the diaper area - topical corticosteroids

Answer: B - Candidal diaper dermatitis - topical antifungal (nystatin or clotrimazole) Explanation: The classic features distinguishing candidal diaper rash from irritant contact dermatitis are: (1) satellite lesions (papules/pustules) beyond the main margin, (2) beefy-red, sharply demarcated borders, and (3) involvement of skin folds/creases (whereas irritant dermatitis typically spares folds). Topical nystatin or clotrimazole is the treatment of choice. Topical steroids alone can worsen candidal infection. - Textbook of Family Medicine 9e / Washington Manual

MIXED/INTEGRATED CASE (2 Bonus MCQs)

Q21. A 6-year-old unvaccinated child presents with high fever, rash, and white spots in the mouth. His 8-year-old sister has a pruritic vesicular rash with lesions in multiple stages. Which single investigation can confirm both diagnoses simultaneously and differentiate them?

A) Tzanck smear - multinucleated giant cells seen only in varicella
B) Clinical diagnosis alone is sufficient; no investigation needed
C) RT-PCR for measles virus (nasopharyngeal swab) and VZV PCR from vesicle fluid
D) Measles IgM alone confirms both

Answer: C - RT-PCR for measles virus (nasopharyngeal swab) and VZV PCR from vesicle fluid Explanation: RT-PCR is increasingly the gold standard for measles confirmation (more sensitive than IgM as incidence falls). For varicella, PCR from vesicle fluid is highly sensitive and specific. Note: Tzanck smear shows multinucleated giant cells in BOTH VZV and HSV - it cannot differentiate the two. - Red Book 2021 / Harrison's 22E

Q22. A 45-year-old HIV-positive patient with CD4 count of 50 cells/μL presents with white oral plaques (candidiasis) AND extensive annular, scaly plaques on the skin (dermatophytosis). Which antifungal has activity against BOTH Candida AND dermatophytes and could be used as a systemic agent in this immunocompromised patient?

A) Nystatin (topical only, not absorbed systemically)
B) Itraconazole (active against both Candida and dermatophytes)
C) Terbinafine (active only against dermatophytes, limited anti-Candida activity)
D) Griseofulvin (active only against dermatophytes)

Answer: B - Itraconazole (active against both Candida and dermatophytes) Explanation: Itraconazole is a broad-spectrum azole with activity against both Candida species and dermatophytes (tinea infections). Terbinafine is primarily fungicidal against dermatophytes but has limited anti-Candida efficacy. Nystatin is not systemically absorbed. Griseofulvin is only used for dermatophytes. In immunocompromised patients with dual fungal infections, itraconazole or fluconazole (for Candida) with a separate agent for dermatophytes, or itraconazole alone, is a rational approach. - Dermatology 2-Volume Set 5e

Summary Table

Topic	MCQs	Key Tested Concepts
Measles	Q1-Q5	Koplik's spots, infectivity period, SSPE, giant cell pneumonitis, vaccine schedule
Chickenpox	Q6-Q10	Pleomorphic rash, adult pneumonia, VZV latency, VariZIG, Reye syndrome
Dermatophytosis	Q11-Q15	Tinea gladiatorum, Majocchi granuloma, tinea cruris vs. candida, kerion, onychomycosis
Candidiasis	Q16-Q20	Germ tube test, antibiotic-related overgrowth, catheter-related candidemia, RVVC, diaper rash
Mixed	Q21-Q22	Diagnostic tools, antifungal spectrum in immunocompromised

All MCQs are single-best-answer format with detailed explanations, sourced from Harrison's 22E, Red Book 2021, Fitzpatrick's Dermatology, Jawetz Medical Microbiology 28E, Goldman-Cecil Medicine, Washington Manual, and Textbook of Family Medicine 9e.

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