Analysis of bone marrow plasma cells in patients with solitary bone plasmacytoma.

Local radiotherapy is the treatment of choice for solitary bone plasmacytoma (SBP) and the role of adjuvant systemic chemotherapy in preventing progression to multiple myeloma (MM) is controversial. The purpose of this study was to examine the presence of systemic disease in the form of neoplastic plasma cells (PC) in bone marrow of patients with SBP. Flow cytometric immunophenotyping of PC was carried out on bone marrow aspirate of 7 patients using monoclonal antibodies: CD19 FITC, CD45 FITC, CD20 FITC, CD52 PE, CD117 PE, CD56 PE, CD38 PerCP-Cy5.5, CD138 APC, anti-kappa (κ) FITC and anti-lambda (λ) PE. The neoplastic as well as normal PC were identified in bone marrow aspirate of all the patients at the time of diagnosis; the neoplastic PC ranged from 0.1%to 0.7% of all BM cells and 33.5% to 89.7% of total BMPC. The κ:λ ratio was normal in all the samples ranging from 0.5% to 1.6%. The present work shows the presence of systemic disease in the form of neoplastic PC in bone marrow of patients with SBP. Prospective studies would be required to study if the levels of neoplastic PC in the bone marrow may help us identify patients who are likely to progress to overt MM and benefit from systemic chemotherapy.