A CASE OF PRIMARY PLASMOCYTOMA ARISING IN THE THYROID

Abstract

We experienced a case of primary plasmocytoma arising in the thyroid. A 76-year-old female visited our hospital complaining of a tumor on the right side of the neck. The tumor locating at the posterior part of the right lobe of thyroid was 4.0×3.5 cm in size, with smooth surface, elastic hard, and well-defined border. It was mobable but slightly restricted. Ultrasonography revealed a tumor picture of irregular margin, internal unequal, and slightly unclear border. Scintigram showed a cold nodule at 99mTc and accumulated picture at 201Tl. A possible malignancy could not be denied, right thyroid lobectomy, paratracheal and parathyroidal lymph nodes dissection being done on October 1, 1990. The excised tumor was 3.8×3.5×2.4 cm in size without any infiltration into the adjacent organs. It could be easily removed. Histopathologic examination showed that the tumor consisted of plasma-like cells, leading to a diagnosis of plasmocytoma. Chronic thyroiditis could be seen in the surrounding thyroid tissues.Immunohistochemical tests resulted in positive against IgG and lambda chain. No abnormalities were noted in bone marrow puncture, general bone X-P, and bone scintigram. No urinary Bence-Jones protein nor blood M protein were determined. Only 12 cases of primary plasmocytoma arising in the thyroid, including this case, can be collected from the literature in this country.