PLASMA-CELL LESIONS OF THE THYROID - REPORT OF A CASE OF SOLITARY PLASMACYTOMA AND A REVIEW OF THE LITERATURE

We report a ease of a solitary plasmacytoma arising from a thyroid wit h longstanding Hashimoto's disease, and diagnosed by fine-needle aspir ation cytology. Serum protein electrophoresis revealed an M-spike in t he gamma-globulin region due to monoclonal IgG-lambda immunoglobulin. The thyroid tumor was treated with near-total thyroidectomy and irradi ation, and the patient was well 6 years after surgery without evidence of multiple myeloma. The serum M-spike disappeared after the tumor re section and radiation therapy. Plasma cell lesions of the thyroid repo rted in the world literature are extensively reviewed. Solitary plasma cytomas occur most commonly in patients with Hashimoto's disease, and must be distinguished from plasma cell granulomas and involvement of t he thyroid in multiple myeloma. Plasmacytomas should be considered in the differential diagnosis of a rapidly enlarging thyroid mass in a pa tient with known Hashimoto's disease.