METASTASES TO THE THYROID-GLAND - DIAGNOSIS BY ASPIRATION CYTOLOGY

The purpose of this study was to document the incidence, nature and so urce of neoplasms metastatic to the thyroid gland which were diagnosed by fine needle aspiration (FNA) cytology. In the seven year period fr om 1986 to 1992, 21 cases were identified with metastatic malignancies in FNA specimens from the thyroid. This represented 7.5% of neoplasti c thyroid lesions aspirated in this unit. All patients presented clini cally with thyromegaly or discrete nodules. Only five patients were kn own to have malignancies of other sites prior to FNA. The majority of metastatic nodules were bronchogenic in origin (nine). The gastrointes tinal tract (five) and melanomas (two) were the next most frequent sou rces in the series. Single cases arose in the prostate, larynx, kidney (all carcinomas), and uterus (a leiomyosarcoma). One patient had a th yroid deposit of acute myeloblastic leukemia. This large study demonst rated that tumors of many histological types may involve the thyroid g land, and furthermore, may masquerade as primary thyroid malignancies. Recognition of an alien cell type not only prevents inappropriate thy roid surgery, but may also direct the search for the unsuspected or un known primary. Metastases to the thyroid gland occur more frequently t han is generally appreciated. FNA is the procedure of choice for evalu ation of thyroid nodules in general, and thyroid metastases in particu lar. (C) 1995 Wiley-Liss, Inc.