Plasma cell tumors with neurologic symptoms: cytological findings

Plasma cell neoplasms (plasma cell dyscrasias) are a group of entities characterized by the neoplastic proliferation of a single clone of plasma cells, typically producing a monoclonal immunoglobulin. These tumors can manifest as multiple myeloma, monoclonal gammopathy of undetermined significance, plasma cell myeloma, or plasmacytoma. We report two plasma cell tumors, one of them presented with headache and diplopia, and the second one complained from low back pain. The aspirate exhibited numerous plasma cells in various stage of maturation and was initially diagnosed as extra-skeletal solitary plasmacytoma on fine-needle aspiration cytology (FNAC). Immunohistochemistry demonstrated monoclonal expression of light immunoglobulin chains together with demonstration of CD 38 positivity. Systematic approach such as bone marrow examination, serum protein electrophoresis, skeletal imaging, and urine examination for Bence-Jones proteins were performed for patients. With these investigations, one case was labeled as multiple myeloma with secondary solitary plasmacytoma in pituitary gland and soft tissue and another one as primary extra-skeletal solitary plasmacytoma. Although fine-needle aspiration is a reliable and rapid technique for initial diagnosis, further work-up and clinical follow-up of these patients is necessary to rule out multiple myeloma. Because of cytomorphological similarity between plasma cells and endocrine cells, EMP of sellar region may be confused with pituitary adenoma especially at the time of intraoperative consultation.