Co-existence of Untreated Chronic Lymphocytic Leukaemia and Acute Myeloid Leukaemia: A Rare Case of Synchronous Dual Haematological Malignancy

The occurrence of Acute Myeloid Leukaemia (AML) or Myelodysplastic Syndrome (MDS) in patients with Chronic Lymphocytic Leukaemia (CLL) is rare. In most of the reported cases, AML occurs after treatment of CLL with cytotoxic drugs suggesting that AML may be a secondary leukaemia (therapy-related AML). AML or MDS occurring in untreated CLL patients is extremely rare with isolated case reports. Herein, we report the case of a 74-year-old male patient who was diagnosed four months back to have chronic B cell lymphoproliferative disorder, from an outside centre. The patient did not receive any treatment. Because of intermittent fever and increased fatigability, he came to our centre. Peripheral blood smear and bone marrow studies showed a dual population of atypical cells-one population of large immature cells with opened-up chromatin, prominent nucleoli, and another population of small atypical lymphocytes with clumped chromatin. Around 10% of immature cells showed Myeloperoxidase (MPO) positivity. Flow cytometric analysis also showed two separate populations of cells. The immunophenotype of one population was compatible with AML, with monocytic differentiation, and the second population showed features of CLL. A diagnosis of coexistent CLL and AML was given. The awareness of the co-existence of dual haematological malignancy, thorough morphological evaluation, and flow cytometric immunophenotyping will lead to accurate diagnosis of these combined malignancies.