Approach to Pancytopenia - Ward & Exam (MRCP/FCPS Part 2)

Definition

• Haemoglobin < 13 g/dL (men) / < 12 g/dL (women)
• WBC < 4,000/µL (or ANC < 1,500/µL)
• Platelets < 150,000/µL

The Pathophysiological Framework (Memorise This First)

Frameworks for Internal Medicine - p. 361-366; Harrison's 22e - Chapter 107

History Taking - Systematic Approach

1. Symptoms of Pancytopenia Itself

• Fatigue, exertional dyspnoea, reduced exercise tolerance
• Palpitations, chest pain (cardiovascular compromise in severe anaemia)
• Pallor noticed by patient/family

• Recurrent/severe infections, fevers, rigors
• Oral ulcers, mucositis
• Specific infective symptoms (chest, urinary, skin)

• Easy bruising, petechiae, purpura
• Prolonged bleeding from cuts
• Epistaxis, gum bleeding
• Heavy menstrual periods (women)
• Haematuria, melaena (more severe)

2. Aetiology-Directed History

Drug and Toxin History (CRITICAL - often missed)

• Chemotherapy or radiation - most obvious
• Antibiotics: chloramphenicol (bone marrow toxicity, unique vacuoles on BM biopsy), linezolid, cotrimoxazole
• Antithyroid drugs: methimazole, propylthiouracil (agranulocytosis + aplasia)
• NSAIDs: indomethacin, phenylbutazone
• Anti-epileptics: carbamazepine, phenytoin
• Methotrexate, azathioprine, mycophenolate
• Alcohol: direct marrow toxin, associated folate deficiency, causes reversible pancytopenia or selective thrombocytopenia
• Arsenic/heavy metals: ask about recurrent GI symptoms, peripheral neuropathy, hair loss - a classic MRCP/FCPS vignette (arsenic poisoning by spouse!)

Nutritional History

• Dietary habits - strict vegan/vegetarian diet → B12 deficiency
• Alcohol use → folate deficiency + direct toxicity
• Malabsorption symptoms: diarrhoea, steatorrhoea, weight loss → coeliac disease, Crohn's

Infective History

• HIV risk factors (sexual history, IV drug use, transfusions)
• TB contacts, travel to endemic areas, night sweats, weight loss
• Viral infections: recent EBV (infectious mononucleosis), CMV, parvovirus B19
• Leishmaniasis: months of fever, weight loss, splenomegaly in a traveller from endemic region (Mediterranean, South Asia, East Africa) - classic MRCP vignette

Travel History

• Tropical travel raises suspicion for leishmaniasis, malaria, brucellosis, enteric fever

Past Medical History

• Autoimmune conditions: SLE (pancytopenia is a diagnostic criterion!), rheumatoid arthritis
• Known liver disease → cirrhosis + hypersplenism
• Prior haematological conditions
• HIV status
• Pregnancy (ask in all women of reproductive age)
• Thyroid disease and treatment

Family History

• Inherited bone marrow failure syndromes in children/young adults:
  • Fanconi anaemia: short stature, radial ray defects, café-au-lait spots
  • Dyskeratosis congenita: nail dystrophy, oral leucoplakia, skin pigmentation
  • Shwachman-Diamond syndrome: pancreatic exocrine insufficiency

Constitutional/B-symptoms

• Fever > 38°C, drenching night sweats, weight loss > 10% in 6 months → lymphoma, leukaemia, TB

Social History

• Occupational exposures: benzene, pesticides, radiation (industrial)
• Alcohol intake (quantify)

Physical Examination - System by System

General Inspection

• Pallor (conjunctival, palmar)
• Jaundice → haemolysis, liver disease, megaloblastic anaemia
• Petechiae, purpura, bruising
• Weight (cachexia → malignancy, TB)
• Nutritional status

Skin and Nails

Mouth and Oropharynx

• Oral ulcers → neutropenia
• Angular stomatitis, glossitis → B12/folate deficiency
• Oral leucoplakia → dyskeratosis congenita
• Thrush → immunosuppression

Lymph Nodes

• Lymphadenopathy is NOT a feature of aplastic anaemia - its presence should prompt you to think infection or lymphoma/leukaemia instead
• Generalised lymphadenopathy + elevated LDH → lymphoma
• Cervical nodes + tonsillar enlargement + splenomegaly → EBV/infectious mononucleosis

Abdomen

• Splenomegaly - most important finding
  • Massive spleen: leishmaniasis, myelofibrosis, CML
  • Moderate: lymphoma, portal hypertension, storage disorders (Gaucher's)
  • Signs of portal hypertension (ascites, caput medusae) + splenomegaly → cirrhosis with hypersplenism
• Hepatomegaly: liver disease, lymphoma, leukaemia, infiltrative disorders
• Hepatosplenomegaly: lymphoma, leukaemia, leishmaniasis, sarcoidosis, myelofibrosis

Neurological

• Peripheral neuropathy + subacute combined degeneration (dorsal column + corticospinal tract) → B12 deficiency
• Peripheral neuropathy + GI symptoms + alopecia → arsenic poisoning

Musculoskeletal

• Symmetrical polyarthritis + splenomegaly + neutropenia → Felty syndrome (RA triad)
• Radial ray defects (absent thumbs) → Fanconi anaemia

Eyes

• Fundoscopy: flame haemorrhages, Roth spots → severe anaemia, infective endocarditis
• Uveitis → sarcoidosis, lymphoma

Putting It Together: Clue Clusters for Differentials

Initial Investigations (Ward-Level)

Tier 1 - Order Immediately

1. CBC with differential - repeat to confirm
2. Peripheral blood film - single most important bedside investigation
   • Blasts → leukaemia (urgent)
   • Hypersegmented neutrophils + oval macrocytes → megaloblastic
   • Teardrop cells (dacrocytes) + nucleated RBCs → myelofibrosis
   • Abnormal lymphocytes → lymphoma/viral
   • Microangiopathic changes → TTP/HUS
3. Reticulocyte count
   • Low → production defect (aplasia, megaloblastic, MDS, infiltration)
   • High/normal → peripheral destruction (hypersplenism, haemolysis)
4. LFTs, renal function, LDH, uric acid
5. B12 and folate levels
6. Coagulation screen (PT, APTT) - DIC, liver disease
7. HIV serology
8. Viral serology: EBV, CMV, hepatitis B and C
9. ANA, dsDNA, complement → SLE screen
10. Abdominal ultrasound - spleen size (>10 cm = splenomegaly), liver morphology, portal hypertension

Tier 2 - Guided by Clinical Context

• TSH (thyroid disease)
• Haematinics: iron studies, copper level (copper deficiency can mimic MDS)
• Blood cultures if febrile
• Bone marrow aspirate and trephine biopsy (BMAT) - indicated in most cases where cause is not obvious
• Flow cytometry (PNH screen, leukaemia/lymphoma immunophenotyping)
• Cytogenetics (MDS, leukaemia)
• Vitamin B12 absorption tests / intrinsic factor antibodies → pernicious anaemia
• Ferritin, serum iron (haemophagocytic lymphohistiocytosis - very elevated ferritin)
• Leishmaniasis serology / bone marrow for Leishman-Donovan bodies if travel history

When to Call Haematology Urgently

• Blasts on blood film (acute leukaemia)
• Severe aplastic anaemia (ANC < 200/µL, platelets < 20,000, reticulocytes < 20,000)
• Suspected PNH
• Lymphoma/myelofibrosis on blood film
• Haemophagocytic lymphohistiocytosis (fever + massive splenomegaly + very high ferritin + cytopenias)

MRCP/FCPS Exam High-Yield Points

1. Aplastic anaemia: no organomegaly, no lymphadenopathy, hypocellular bone marrow - diagnosis by exclusion after thorough workup
2. PNH: pancytopenia + Coombs-negative haemolytic anaemia + venous thrombosis at unusual sites (Budd-Chiari, portal vein) - diagnosed by flow cytometry (absent CD55/CD59)
3. Megaloblastic anaemia: most common cause in developing world; macrocytosis + hypersegmented neutrophils + neurological symptoms; B12 is associated with subacute combined degeneration of the cord (NOT folate)
4. MDS: elderly patient, macrocytic anaemia, dysplastic cells on film, may evolve to AML
5. Felty syndrome: RA + splenomegaly + neutropenia (not full pancytopenia typically, but can be)
6. Hairy cell leukaemia: middle-aged man, massive splenomegaly, no lymphadenopathy, "fried egg" cells on film, TRAP-positive; classic MRCP topic
7. Leishmaniasis: do not miss in a traveller - bone marrow biopsy shows Leishman-Donovan bodies (amastigotes within macrophages)
8. Bone marrow biopsy is usually indicated unless the cause is obvious (e.g., clear portal hypertension with cirrhosis)
9. Lymphadenopathy in pancytopenia = infection or malignancy, NOT aplastic anaemia
10. Reticulocyte count is your first branch point - low = production failure; high = destruction/sequestration

Pancytopenia - FCPS Part 2 Short/Long Case Master Guide

The Examiner's Mental Model

1. Can you safely assess a sick patient (structured, systematic)
2. Can you distinguish common from rare, benign from malignant

MASTER MNEMONIC: "HIIH" - The 4 Mechanisms

Hypoplasia - Ineffective hematopoiesis - Infiltration - Hypersplenism

The SHORT CASE Approach (10-15 min)

Step 1 - Opening Statement (30 seconds)

• Pallor (anaemia)
• Petechiae / purpura / bruising (thrombocytopenia)
• Jaundice (megaloblastic, haemolysis, liver disease)
• Lymphadenopathy (malignancy, infection)
• Splenomegaly (the single most informative finding)

Step 2 - The Spleen is Your Pivot

The LONG CASE Approach

History Structure - Mnemonic: "PAID FACTS"

P - Presenting symptoms (anaemia / bleeding / infection features) A - Associated symptoms (B-symptoms, jaundice, joint pains) I - Iatrogenic / drugs (chemotherapy, chloramphenicol, MTX, antithyroids, carbamazepine) D - Dietary & nutritional (vegan diet, alcohol, malabsorption) F - Family history (inherited bone marrow failure in young patients) A - Autoimmune history (SLE, RA) C - Constitutional symptoms (fever, night sweats, weight loss → B-symptoms) T - Travel history (tropics → leishmaniasis, malaria, brucellosis) S - Social history (alcohol, occupational benzene/radiation exposure)

Physical Examination Structure - Mnemonic: "SCALP-N"

S - Skin/Mucous membranes (pallor, petechiae, jaundice, butterfly rash, café-au-lait, spider naevi) C - Cervical/Axillary/Inguinal nodes (lymphadenopathy → malignancy/infection; ABSENCE → aplastic anaemia) A - Abdomen (liver size, spleen size, ascites, caput medusae) L - Limbs (peripheral neuropathy, radial ray defects, nail dystrophy) P - Peripheral blood smear findings to correlate N - Neurological (subacute combined degeneration → B12)

Classic Examination Clue Clusters - Exam Favourites

Mnemonic for Causes by Age: "YVAM"

Young patient → aplastic anaemia, inherited marrow failure, PNH, ALL Vegan / elderly → B12 megaloblastic Aged (>60) → MDS, AML, lymphoma, myeloma Middle-aged traveller → leishmaniasis, brucellosis, viral

Questions Professors WILL Ask in FCPS Part 2

Tier 1 - They Will Always Ask These

1. "What is your single most important bedside investigation?"
   • Answer: Peripheral blood film - it costs nothing and tells you everything
2. "You see no lymphadenopathy and no splenomegaly - what is your top diagnosis?"
   • Answer: Aplastic anaemia (lymphadenopathy in pancytopenia = NOT aplastic)
3. "What is the single most discriminating investigation you'd order first?"
   • Answer: Reticulocyte count - it splits production failure from destruction/sequestration
4. "How do you classify severity of aplastic anaemia?"
   • Severe AA (SAA): BM cellularity < 25% + any 2 of: (neutrophils < 0.5 × 10⁹/L, platelets < 20 × 10⁹/L, reticulocytes < 20 × 10⁹/L)
   • Very severe AA (VSAA): same as SAA but neutrophils < 0.2 × 10⁹/L
5. "What is the triad of PNH?"
   • Pancytopenia + Haemolysis (Coombs-negative) + Venous thrombosis at unusual sites
6. "How do you diagnose PNH?"
   • Flow cytometry - absent CD55 and CD59 on RBCs and granulocytes
7. "What organism do you look for in the bone marrow of a patient with massive splenomegaly returning from South Asia?"
   • Leishman-Donovan bodies (amastigotes of Leishmania donovani within macrophages)
8. "What blood film finding tells you this patient needs urgent haematology?"
   • Blast cells → acute leukaemia, do not delay

Tier 2 - Tricky Professor Traps

1. "A patient has B12 deficiency. Should you give folate?"
   • NOT before replacing B12 - giving folate alone in B12 deficiency can precipitate or worsen subacute combined degeneration of the cord (SCD)
2. "Hairy cell leukaemia - what is specific on the blood film?"
   • Dry tap on aspirate (fibrosis), cells with "fried egg" / hairy cytoplasmic projections, TRAP stain positive, CD103+
3. "Your patient has pancytopenia and is COOMBS NEGATIVE with haemolysis - what does that tell you?"
   • Think PNH (complement-mediated, not antibody-mediated, hence Coombs-negative)
4. "What is Felty syndrome?"
   • RA + splenomegaly + neutropenia (the triad) - can give pancytopenia
5. "What is the most common cause of pancytopenia in the developing world?"
   • Megaloblastic anaemia (B12/folate deficiency)
6. "What is the relationship between PNH and aplastic anaemia?"
   • They overlap - PNH clones can emerge from aplastic anaemia; both share immune-mediated stem cell destruction. 5-10% of aplastic patients develop PNH over time
7. "Name an infection that causes pancytopenia via haemophagocytosis"
   • EBV, CMV, parvovirus B19, TB - all can trigger Haemophagocytic Lymphohistiocytosis (HLH)

TRICKY CONCEPTS TO REMEMBER

1. The "No Lymphadenopathy" Rule

• Aplastic anaemia = NO lymphadenopathy, NO splenomegaly
• If you see either → reconsider (lymphoma, leukaemia, infection)

2. PNH Thrombosis is "Backwards"

• Thrombosis typically at unusual venous sites: hepatic vein (Budd-Chiari), portal vein, cerebral sinuses
• A young patient with Budd-Chiari + no liver disease = PNH until proven otherwise

3. B12 vs Folate Neurological Rule

"B12 causes B(rain) and Spinal cord disease - Folate does NOT"

• Subacute combined degeneration = B12 ONLY
• Folate deficiency can cause NTDs in pregnancy but NOT SCD

4. Reticulocyte Count Interpretation

5. Drug Causes - Mnemonic "CALM-ABC"

Chloramphenicol - Antithyroid (methimazole/PTU) - Linezolid - Methotrexate - Anticonvulsants (carbamazepine) - Benzene - Chemotherapy

6. Bone Marrow is Hypocellular vs Hypercellular - Key Decision

7. Hepatitis + Aplastic Anaemia

• Seronegative hepatitis (unknown viral agent) is a well-recognized trigger for aplastic anaemia
• Acute hepatitis → aplastic anaemia within weeks to months
• Examiner loves this because it surprises candidates

8. MDS vs Megaloblastic - How to Tell Apart

9. HLH - The Killer Diagnosis Not to Miss

• Fever + massive splenomegaly + pancytopenia + ferritin > 500 ng/mL (often > 10,000)
• Bone marrow shows macrophages engulfing blood cells (haemophagocytosis)
• Triggered by EBV, CMV, TB, lymphoma
• HScore - used to calculate probability of HLH

10. Fanconi Anaemia Classic FCPS Vignette

• Child with pancytopenia + short stature + absent thumbs / radial aplasia + café-au-lait spots
• Confirmed by chromosomal breakage test (DEB/MMC test)
• High risk of AML and solid tumours

Causes Mnemonic - "MIAMI BLAST" (for ALL causes)

M - Megaloblastic anaemia (B12/folate) I - Infiltrative (leukaemia, lymphoma, myelofibrosis, metastases, TB, Gaucher's) A - Aplastic anaemia (idiopathic, drugs, toxins, infections) M - Medications / toxins (chloramphenicol, benzene, MTX, alcohol) I - Infections (HIV, EBV, CMV, TB, leishmaniasis, HLH) B - B12/folate already covered (reinforcer) L - Liver disease / hypersplenism (cirrhosis, portal hypertension) A - Autoimmune (SLE, Felty, AIHA) S - Storage / systemic (Gaucher's, sarcoidosis, PNH) T - Tropical (leishmaniasis, malaria, brucellosis)

Blood Film Findings - Rapid Recognition Table

Summary Algorithm for the Viva

PANCYTOPENIA confirmed on CBC
        |
        ↓
PERIPHERAL BLOOD FILM + RETICULOCYTES
        |
  ________|________
  |               |
BLASTS?        No blasts
  |               |
Leukaemia    Reticulocytes low?
(URGENT)      YES → Production failure
              NO → Hypersplenism / destruction
                    |
              BONE MARROW
              Hypocellular → Aplasia
              Hypercellular + dysplasia → MDS/Megaloblastic
              Infiltrated → Malignancy/TB/Gaucher's

One-Line Exam Closers (Impress the Examiner)

• "In pancytopenia, lymphadenopathy essentially rules out aplastic anaemia."
• "PNH is the only condition that causes Coombs-negative haemolysis with thrombosis at unusual venous sites."
• "A dry tap on bone marrow aspirate in a middle-aged man with massive splenomegaly = hairy cell leukaemia."
• "Seronegative hepatitis is an underappreciated but well-established trigger for aplastic anaemia."
• "Megaloblastic anaemia is the most common cause of pancytopenia in the developing world - B12 and folate must always be checked before bone marrow biopsy."
• "Very high ferritin (> 10,000) in a febrile patient with pancytopenia = HLH until proven otherwise."