Acute leukaemia — recognition and initial management OSCE station (NEET-PG/INICET)

Candidate instructions

You are the doctor in the emergency department. A 62-year-old man has been referred with fatigue, fever and a petechial rash. His blood count shows pancytopenia with a high white-cell count and 50 percent blasts. You have 8 minutes to assess and begin managing him, and 2 minutes for examiner questions.

Vital signs (provided): temperature 38.6 deg C, pulse 108, BP 104/64 mmHg, RR 22, SpO2 96 percent on air. Hb 66 g/L, WBC 64 x 10^9/L (50 percent blasts), platelets 18 x 10^9/L.

Candidate tasks

1. Take a focused, rapid history including symptom time-course, bleeding/infection, drug/chemical exposure, prior haematological disease and family history.
2. Perform a focused general and haematological examination (pallor, purpura, gums, nodes, liver, spleen, fundi, infection focus, neurological status).
3. State your immediate investigations and their rationale, including what you would look for on the blood film.
4. Outline your immediate management, identifying the life-threatening complications that need action now.
5. Communicate your plan and disposition clearly to the examiner.

Examiner checklist (mark each as done / partial / not done)

• Recognises this as probable acute leukaemia (marrow failure plus circulating blasts) and triggers an urgent haematology referral.^[1]
• Examines for and comments on marrow failure (anaemia, bleeding/petechiae, infection focus) and infiltration (gum hypertrophy, hepatosplenomegaly, lymphadenopathy).^[1]
• Orders the correct immediate investigations: review of the blood film (looking for Auer rods, promyelocytes), coagulation including fibrinogen and D-dimer, U&E, urate, phosphate, calcium, LDH, lactate, blood cultures, and bone marrow with flow cytometry, cytogenetics and molecular testing.^[1]
• Identifies that a high WBC with blasts is a tumour lysis and leucostasis risk, and starts aggressive IV hydration with tumour lysis prophylaxis (allopurinol, or rasburicase if high burden).^[2]
• Recognises that fever in this cytopenic patient is febrile neutropenia/neutropenic sepsis and states the need for empirical broad-spectrum IV antibiotic (e.g. piperacillin-tazobactam) within one hour, taking cultures first but not delaying antibiotics.^[1]
• Specifically asks about/signals acute promyelocytic leukaemia as the subtype to exclude urgently: states that DIC with low fibrinogen + promyelocytes/Auer rods means start ATRA on suspicion, before genetic confirmation.^[3]
• Plans supportive care: transfusion of red cells for symptomatic anaemia and platelets for thrombocytopenia/bleeding (proactive platelet/fibrinogen targets if APL), and venous access.
• Communicates the diagnosis, the emergency complications and a clear disposition (admit haematology, supportive care pending marrow results).

Model answer / expected standard

This is acute leukaemia presenting with the triad of marrow failure (anaemia causing fatigue, thrombocytopenia causing the petechial rash/bleeding, neutropenia causing fever) plus circulating blasts (50 percent). The priority is to (1) recognise the life-threatening complications — febrile neutropenia (empirical piperacillin-tazobactam within the hour after cultures), tumour lysis syndrome (high WBC — hydration plus allopurinol or rasburicase and close electrolyte monitoring), leucostasis (if symptomatic — leucopheresis), and APL with DIC (check coagulation; if the film shows promyelocytes/Auer rods or the fibrinogen is low, start ATRA on suspicion) — and (2) secure the diagnosis with an urgent bone marrow (aspirate + trephine) sent for morphology, flow cytometry (lineage), cytogenetics and molecular testing (PML-RARA, FLT3, NPM1, BCR-ABL1). Transfuse red cells and platelets as needed, establish venous access, and admit under haematology. Definitive treatment (7+3 for AML with midostaurin if FLT3-mutated; ATRA + arsenic for APL; ALL-type chemo + intrathecal if lymphoid) follows the lineage and risk results.^[1][2][3]

Common errors

• Treating the fever as a simple infection and missing neutropenic sepsis (delaying empirical IV antibiotics for culture results).
• Not recognising acute leukaemia from the combination of marrow failure and blasts, or assuming blasts are a reactive phenomenon.
• Failing to check coagulation and fibrinogen — and therefore missing APL/DIC and delaying ATRA.
• Not starting tumour lysis prophylaxis before the blast count is treated.
• Ordering a marrow but omitting the flow cytometry, cytogenetics and molecular studies that determine lineage, risk and targeted therapy.
• Not transfusing platelets to a safe level before any procedure, or attempting invasive procedures through a coagulopathy.

References

The station is built on the Khwaja Nature Reviews primer of AML, the Howard review of tumour lysis syndrome, and the Lo-Coco APL0406 trial of ATRA plus arsenic.^[1][2][3]

References3ShowHide

1. [1]Khwaja A, Bjorkholm M, Gale RE, et al. Acute myeloid leukaemia. Nature Reviews Disease Primers, 2016.PMID 27159408
2. [2]Howard SC, Jones DP, Pui CH. The tumor lysis syndrome. New England Journal of Medicine, 2011.PMID 21561350
3. [3]Lo-Coco F, Avvisati G, Vignetti M, et al. Retinoic acid and arsenic trioxide for acute promyelocytic leukemia. New England Journal of Medicine, 2013.PMID 23841729