Two cases of nonsecretory multiple myeloma presenting as primary plasma cell leukemia.

Plasma cell leukemia (PCL) is a rare variant of multiple myeloma (MM) with a poor prognosis. Nonsecretory myeloma is also a rare form of MM characterized by the absence of detectable M-protein in the serum and urine. This report describes two cases of nonsecretory PCL. The first patient was an 85-year-old man in whom the lack of monoclonal immunoglobulins made it difficult to make a diagnosis because the malignant cells showed an atypical morphology. He died of rapid disease progression before starting chemotherapy. The second patient was a 78-year-old woman whose tumor cells displayed a typical plasma cell morphology. She was successfully treated with bortezomib-containing chemotherapy.