Implications of an unusual acute leukaemia phenotype on the care of a South African Jehovah's Witness patient.

An HIV-negative South African woman in her 50s presented to hospital with fatigue. She had no medical history and is a Jehovah's Witness. Her full blood count revealed macrocytic anaemia and severe thrombocytopenia. On smear review, there were ±66% blasts with no lineage discerning morphological features. Peripheral blood flow cytometry revealed a blast population that expressed B-cell (CD19 dim, cCD79a dim, CD10 dim, CD22 moderate), T/NK-cell (CD7) and myeloid markers (HLA-DR, CD33, CD117). However, antigen combinations did not fulfil the requirements for specific lineage assignment. The bone marrow aspirate and trephine biopsy were hypercellular with diffuse involvement of blasts. Myeloperoxidase positivity was subsequently confirmed on cytochemistry and immunohistochemistry. The final diagnosis was an acute myeloid leukaemia with expression of aberrant lymphoid markers and monocytic cytochemistry. Delays in lineage assignment can derail timely induction, shake patient confidence and postpone the doctor-patient treatment discussions. This is particularly important in already vulnerable populations.