Clinicopathological and laboratory parameters of plasma cell leukemia among Indian population

Abstract

Background: Plasma cell leukemia (PCL) is a rare and aggressive plasma cell neoplasm distinguished by extensive clonal expansion of plasma cells in the bone marrow (BM) and peripheral blood (PB). PCL is divided into two subtypes: primary (pPCL) originates de novo without preceding multiple myeloma, while secondary (sPCL) comprises a leukemic modification that occurs as a late manifestation from previous multiple myeloma (MM). pPCL and sPCL are clinically and biologically two different entities. The molecular mechanisms of the development of PCL, either primary or secondary, remain poorly understood. We aim to present 5 years of data on clinical profiles and treatment outcomes of pPCL and sPCL patients treated at our cancer hospital in India and to find a predictive parameter of the development of PCL in cases of MM.

Methods: In this study, we retrospectively reviewed and evaluated the clinicopathological features, laboratory parameters, immunophenotypic profile, and patient outcomes of 17 PCL cases diagnosed among 180 plasma cell dyscrasia patients during the study period to establish a correlation between pPCL & sPCL for diagnosis and management of PCL.

Results: A total of 17 PCL patients were diagnosed among 180 plasma cell dyscrasia patients during the study period. Among PCL patients, 9 cases had pPCL (52.94% of all PCL patients), and 8 cases had sPCL (47.06% of all PCL patients). Peculiar differences were seen between the two PCL types. Both types of PCL had a younger age at the time of diagnosis, having elevated BM plasma cell infiltration percentage, frequent anemia, thrombocytopenia, elevated beta-2-microglobulin (B2M) levels, raised LDH levels, and positive M-protein in both serum and urine. In addition, SFLC assay and Immunofixation assay showed higher κ and lower λ in pPCL compared with sPCL (P<0.05). Higher Renal insufficiency was also observed in pPCL compared to sPCL (P=0.335). The survival and response to treatment of PCL patients remain considerably poor, sPCL exhibit shorter overall survival (OS) than pPCL with (median 1.75 months vs. 7 months respectively, P=0.1682). Plasma cell leukemia (PCL) needs to be diagnosed early and requires prompt initiation of treatment before patients get complications.

Conclusion: Our study characterizes the clinical and laboratory features of pPCL and sPCL and may aid physicians in prognosticating the course of disease of their patients. However, future multicentre studies are the need of the hour to develop accurate diagnostic criteria and establish the efficacy of therapeutic regimens.

Keywords: Plasma cell leukemia (PCL); leukemia; multiple myeloma.

Figure 1

Bone marrow examination of PCL cases. A. Peripheral blood smear showing plasma cells in Giemsa stain (20×). B. Peripheral blood smear showing plasma cells in Giemsa stain (20×) in 40×. C. Peripheral blood smear showing plasma cells in Giemsa stain (20×) in oil immersion lens (100×).