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

This study presents 19 patients with extramedullary plasma-cell tumors diag nosed by fine-needle aspiration (FNA) cytology together with immunocytochem istry. Eight patients had primary extramedullary plasmacytoma, while 11 pat ients had tumors secondary ro myeloma. The most common localization was sof t tissue (9 cases), followed by lymph nodes (5), scalp (3), and oral and na sal mucosa (2). Ail FNA smears were cellular, and 12 cases, showed dissocia ted monomorphic plasma cells. Seven cases showed a dominance of immature ba re nuclei, which made them difficult to diagnose conclusively using cytomor phology only. Immunocytochemistry demonstrated monoclonal expression of lig ht immunoglobulin chains in all cases, which, together, with demonstration of CD 38 positivity and cytomorphology allowed a conclusive diagnosis of pl asmacytoma. (C) 1999 Wiley-Liss. Inc.