Abstract
Simple SummaryExtramedullary disease can occur either in multiple myeloma at the initial diagnosis or relapse or as primary extramedullary plasmocytoma/solitary osseous plasmocytoma. The exact molecular mechanisms underlying extramedullary spread of clonal plasma cells are not fully understood. The aim of our study was to assess further insights into clinical and biological characteristics of different types of extramedullary plasma cell disorders. We show that expression profiles of molecules involved in homing and cytogenetic abnormalities differ between various types of plasma cell dyscrasias, indicating the contrasting biology of these diseases. Background: Extramedullary plasma cell (PC) disorders may occur as extramedullary disease in multiple myeloma (MM-EMD) or as primary extramedullary plasmocytoma (pEMP)/solitary osseous plasmocytoma (SOP). In this study, we aimed to obtain insights into the molecular mechanisms of extramedullary spread of clonal PC. Methods: Clinical and biological characteristics of 87 patients with MM-EMD (n = 49), pEMP/SOP (n = 20) and classical MM (n = 18) were analyzed by using immunohistochemistry (CXCR4, CD31, CD44 and CD81 staining) and cytoplasmic immunoglobulin staining combined with fluorescence in situ hybridization (cIg-FISH). Results: High expression of CD44, a cell-surface glycoprotein involved in cell-cell interactions, was significantly enriched in MM-EMD (90%) vs. pEMP/SOP (27%) or classical MM (33%) (p < 0.001). In addition, 1q21 amplification by clonal PC occurred at a similar frequency of MM-EMD (33%), pEMP/SOP (57%) and classical MM (44%). Conversely, del(17p13), t(4;14) and t(14;16) were completely absent in pEMP/SOP. Besides this, 1q21 amplification was identified in 64% of not paraskeletal samples from MM-EMD or pEMP compared to 9% of SOP or paraskeletal MM-EMD/pEMP and 44% of classical MM samples, respectively (p = 0.02). Conclusion: Expression of molecules involved in homing and cytogenetic aberrations differ between MM with or without EMD and pEMP/SOP.
Highlights
Extramedullary plasma cell (PC) dyscrasias may occur either in multiple myeloma (MM) as an extramedullary disease (MM-EMD) or as primary extramedullary plasmocytoma/solitary osseous plasmocytoma (SOP) in the absence of MM-defining criteria [1,2,3]
Extramedullary PC disorders are characterized by the ability of clonal PC to become independent from the bone marrow (BM) microenvironment and infiltrate other organs and/or circulate freely in the blood [6]. primary extramedullary plasmocytoma (pEMP)/SOP generally has a favorable prognosis with a 10-year survival rate of around 75% [2,7]
We found significantly higher CD44 expression in clonal PC (cPC) derived from MM-EMD compared to those from classical MM or pEMP/SOP
Summary
Extramedullary plasma cell (PC) dyscrasias may occur either in multiple myeloma (MM) as an extramedullary disease (MM-EMD) or as primary extramedullary plasmocytoma (pEMP)/solitary osseous plasmocytoma (SOP) in the absence of MM-defining criteria [1,2,3]. The CD81 expression status may play a role in disease progression and extramedullary spread of cPC disorders. Extramedullary plasma cell (PC) disorders may occur as extramedullary disease in multiple myeloma (MM-EMD) or as primary extramedullary plasmocytoma (pEMP)/solitary osseous plasmocytoma (SOP). Results: High expression of CD44, a cell-surface glycoprotein involved in cell-cell interactions, was significantly enriched in MM-EMD (90%) vs pEMP/SOP (27%) or classical MM (33%) (p < 0.001). Conclusion: Expression of molecules involved in homing and cytogenetic aberrations differ between MM with or without EMD and pEMP/SOP
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