Rapidly Progressing Plasma Cell Leukemia with Underlying Plasmablastic Morphology: A Rare Case Report of a 25-Year Old Male.

Multiple myeloma constitutes a wide spectrum of diseases, ranging from slow-growing monoclonal gammopathy of undetermined significance to rapidly progressing plasma cell leukemia. It is a very rarely diagnosed hematological malignancy in those less than 30 years of age. A 25-year-old male presented with complaints of fatigue and low-grade fever. On investigation, he was found to have bicytopeina and features of tumor lysis syndrome. Initially, this was thought to be indicative of acute leukemia. However, upon further analysis with bone marrow biopsy, serum protein electrophoresis, and immunofixation, it was determined that the patient had an IgG myeloma with plasmablastic morphology. It rapidly progressed and the peripheral smear started showing clusters of plasma cells suggesting a picture of plasma cell leukemia. The patient succumbed to this aggressive disease despite treatment. This case illustrates that myeloma should also be included in the differential diagnosis for young patients, especially the rare plasmablastic variant, which can be misdiagnosed as acute leukemia. The aggressive morphology also tends to show rapid progression to plasma cell leukemia, which has a poor prognosis.