Fine-needle aspiration cytology and immunocytochemistry of soft-tissue extramedullary plasma-cell neoplasms

This study presents 19 patients with extramedullary plasma-cell tumors diagnosed by fine-needle aspiration (FNA) cytology together with immunocytochemistry. Eight patients had primary extramedullary plasmacytoma, while 11 patients had tumors secondary ro myeloma. The most common localization was soft tissue (9 cases), followed by lymph nodes (5), scalp (3), and oral and nasal mucosa (2). Ail FNA smears were cellular, and 12 cases, showed dissociated monomorphic plasma cells. Seven cases showed a dominance of immature bare nuclei, which made them difficult to diagnose conclusively using cytomorphology only. Immunocytochemistry demonstrated monoclonal expression of light immunoglobulin chains in all cases, which, together, with demonstration of CD 38 positivity and cytomorphology allowed a conclusive diagnosis of plasmacytoma. (C) 1999 Wiley-Liss. Inc.