Concomitant Waldenström Macroglobulinemia/Lymphoplasmacytic Lymphoma and Non-Immunoglobulin M Plasma Cell Neoplasm.

in Archives of pathology & laboratory medicine by Yue Zhao, Philip Petersen, Sophie Stuart, Jiaqi He, Yaping Ju, Luis F Carrillo, Eric D Carlsen, Yi Xie, Alireza Ghezavati, Imran Siddiqi, Ling Zhang, Endi Wang

TLDR

  • The study analyzed 14 cases of concomitant lymphoplasmacytic lymphoma (LPL) and plasma cell neoplasm (PCN) and found that most cases exhibited concordant light-chain restrictions between the 2 neoplasms, suggesting a potential mechanism of transformation from LPL to PCN.

Abstract

The co-occurrence of plasma cell neoplasm (PCN) and lymphoplasmacytic lymphoma (LPL) is rare, and their clonal relationship remains unclear. To evaluate the clinicopathologic characteristics of concomitant LPL/PCN. Retrospectively analyzed clinical and laboratory data of 14 cases. Three patients initially presented with immunoglobulin (Ig) M paraprotein, 1 with IgG paraprotein, and 10 had simultaneous diagnoses of PCN and LPL. In 13 cases, flow cytometry detected both LPL and PCN in marrow biopsies. Furthermore, immunohistochemistry highlighted the 2 neoplastic populations, demonstrating an increased proportion of plasma cells and their expression of cyclin D1, CD56, and/or a non-IgM isotype restriction. All cases exhibited discordant heavy-chain isotypes between LPL and PCN. Thirteen of the 14 cases (92.9%) had concordant light-chain restrictions between the 2 neoplasms, and the remaining case (7.1%) showed discordant light-chain restrictions. Of the 12 patients with follow-up, 5 were treated with myeloma regimens, 2 with LPL regimens, 3 with combined therapy, and 2 with observation alone. Follow-up ranged from 2 to 146 months (median, 12.5 months). One patient died of PCN progression, one died of comorbidity, and 10 patients were alive with or without disease. Survival analysis showed no significant difference from the control. The discordant heavy-chain isotype restrictions between PCN and LPL suggest biclonal B-cell neoplasms, which is supported by PCN's phenotypic distinction, such as the expression of cyclin D1 and/or CD56. However, our series exhibited a tendency toward concordant light-chain restrictions between the 2 neoplasms, raising the possibility that PCN may evolve from LPL through class switching.

Overview

  • This study retrospectively analyzed clinical and laboratory data of 14 cases of concomitant lymphoplasmacytic lymphoma (LPL) and plasma cell neoplasm (PCN) to evaluate their clinicopathologic characteristics.
  • The study aimed to investigate the co-occurrence of LPL and PCN, their clonal relationship, and clinicopathologic characteristics.
  • The authors analyzed the expression of cyclin D1, CD56, and heavy/light-chain isotypes in both LPL and PCN to better understand their relationships.

Comparative Analysis & Findings

  • All 14 cases exhibited discordant heavy-chain isotypes between LPL and PCN, suggesting biclonal B-cell neoplasms.
  • Thirteen of the 14 cases (92.9%) had concordant light-chain restrictions between the 2 neoplasms, and the remaining case (7.1%) showed discordant light-chain restrictions.
  • Flow cytometry detected both LPL and PCN in marrow biopsies in 13 cases, and immunohistochemistry highlighted the 2 neoplastic populations.

Implications and Future Directions

  • The findings suggest that PCN may evolve from LPL through class switching, which is a potential mechanism of transformation from LPL to PCN.
  • Future studies are needed to confirm the clonal relationship between LPL and PCN and to explore the molecular mechanisms underlying the co-occurrence of these two neoplasms.
  • The study's results may have implications for the diagnosis and management of patients with LPL and PCN, particularly in terms of their treatment regimens and monitoring protocols.
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