Synchronous Plasma Cell Myeloma and Acute Myeloid Leukemia in a Therapy-Naïve Patient: A Rare Occurrence

Plasma cell proliferations in patients with acute myeloid leukemia (AML) are rare, whether at presentation or during or after therapy. Interpretation requires correlation with the clinical background, drug history as well as inputs from tests for monoclonal gammopathy and end-organ damage. The major diagnostic issues stem from excluding myeloma alone with a plasmablastic morphology that mimics AML as well as reactive or polyclonal plasmacytosis occurring in a bonafide case of AML alone before rendering a rare diagnosis of true dual pathologies. We report a rare case of concurrent AML and plasma cell myeloma in a 55-year-old lady that posed a significant diagnostic challenge. The patient had significant co-morbidities complicating the clinical picture and was treatment-naïve at the time of diagnosis. Our approach to confirming the diagnosis, as well the challenges faced in flow cytometric analyses are highlighted. The pathogenesis of such dual pathologies remains unresolved, although various conjectures and theories have been propounded in literature.