[Hypoplastic acute promyelocytic leukemia with continuous hypocellular bone marrow after remission]

An 87-year old female presented with unsteady gait and occasional subcutaneous hematomas. Blood examination findings revealed pancytopenia and mild coagulopathy. Both the histopathological evaluation of bone marrow smears and bone marrow biopsy revealed a hypocellular bone marrow. However, APL cells were observed and PML-RARA fusion gene was detected. On the basis of these findings, the patient was diagnosed with hypoplastic acute promyelocytic leukemia. She received ATRA treatment and achieved complete remission (CR) 29 days from the commencement of therapy. After the first CR, she received two courses of ATO as a consolidation therapy. Following the latter treatments, she maintained CR, but a hypoplastic bone marrow was still observed. Hypoplastic AML is defined as AML with a low bone marrow cellularity. It is clinically important to distinguish it from aplastic anemia and hypoplastic MDS. It has been suggested that both cytogenetic and morphological diagnosis are imperative to the differential diagnosis of hypocellular bone marrow.