OSCE STATION 4. Leukopenia / Aplastic Anemia — Peripheral Blood Film & Focused History

Candidate Instructions

Use the case card provided by the examiner. Take a focused history from the patient or the child’s parent, interpret the blood count and peripheral blood-film report, and explain your diagnostic approach and immediate concern.

Clinical Setting and Station Requirements

Use one of the following interchangeable case cards. Both use the blood-results sheet below. The station requires a simulated patient or parent and the printed report; no microscope is required.

• Adult variant: A 29-year-old patient presents with fatigue, recurrent mouth ulcers and easy bruising.
• Pediatric variant: A parent brings an 8-year-old child with fatigue, recurrent mouth ulcers and new bruises.

Blood-Results and Peripheral Blood-Film Report

• Hemoglobin: 7.4 g/dL
• White-cell count: 1.4 × 10⁹/L; absolute neutrophil count: 0.4 × 10⁹/L
• Platelets: 28 × 10⁹/L; reticulocytes: low for the degree of anemia
• Film: reduced white cells and platelets; red cells predominantly normal-sized; no circulating blasts identified.

Expected Student Performance

1. Check for immediate danger. Ask about current fever, appearing acutely unwell, active bleeding, severe breathlessness and fainting. Fever with this neutrophil count requires urgent assessment.
2. Establish the timeline. Ask when fatigue, infections and bruising began; whether blood counts were previously normal; and whether symptoms are worsening.
3. Seek cause-directed history. Ask about recent viral illness, medicines and treatments, toxin or radiation exposure, previous transfusions, and family history of blood disorders. In the child, also ask about growth, development and recurrent infections since infancy.
4. Read the report systematically. Identify the reduced neutrophils, hemoglobin and platelets; note the inadequate reticulocyte response and whether blasts or other abnormal cells are reported.
5. Explain the pattern. This is pancytopenia with impaired red-cell production, raising concern for marrow failure, including aplastic anemia. A blood film alone cannot confirm aplastic anemia or exclude leukemia.
6. Plan the workup. Repeat the blood count and film, review prior results and medicines, and arrange urgent hematology assessment. Select infection, nutritional and other cause-directed tests from the history; bone-marrow examination is needed when marrow failure is suspected.

Model Interpretation and Clinical Conclusion

“The report shows severe neutropenia together with anemia, thrombocytopenia and a low reticulocyte response. This suggests reduced bone-marrow production. Aplastic anemia is an important possibility, but I would not diagnose it from the peripheral film alone. I would assess urgently for infection or bleeding, review possible causes and arrange hematology evaluation with bone-marrow testing.”

For the pediatric variant, include congenital or inherited marrow-failure conditions in the cause-directed assessment, especially if the history began early in life or there are relevant family or developmental findings.

Critical Safety Points

Fever or acute illness with marked neutropenia requires immediate clinical assessment and escalation. Active bleeding with severe thrombocytopenia is also urgent. The absence of blasts on one film does not rule out a serious marrow disorder.

Examiner Viva

1. What is pancytopenia?
   A reduction in red cells, white cells and platelets.
2. Why is the absolute neutrophil count more useful than the total white-cell count?
   It identifies the degree of neutropenia and helps assess infection risk.
3. What does a low reticulocyte response suggest here?
   The marrow is not producing enough new red cells for the degree of anemia.
4. Does this film confirm aplastic anemia?
   No. The blood results raise suspicion; marrow examination showing hypocellularity is needed for confirmation.
5. What extra history matters in a child with unexplained cytopenias?
   Ask about problems since infancy, growth and development, recurrent infections, congenital features and family history.