Plasma Cell Leukaemia

Plasma cell leukaemia is a plasma cell neoplasm in which clonal plasma cells constitute >20% of the total leukocyte count in the blood or the absolute count is >2.0×10⁹/L. The bone marrow is often diffusely and extensively infiltrated, and extramedullary disease at presentation is common. Primary plasma cell leukaemia is rare, and the prognosis is grim. Light chain disease is more common in PCL than myeloma, and approximately 80% of PCL have plasma cells which are CD56-negative.