Thyroid tumors: cytomorphology of medullary, clinically anaplastic, and miscellaneous thyroid neoplasms.

Of 2,012 fine-needle aspirations (FNAs) of the thyroid performed between the years 1984 and 1988, detailed cytomorphologic analysis of 95 cases diagnosed as neoplastic on histology and/or cytology and those that received an equivocal cytodiagnosis are presented in this article. Discussed are medullary thyroid carcinomas (nine cases), clinically anaplastic thyroid tumors (CATT; eight cases), two cases of non-Hodgkin's lymphoma (NHL), and one primary leiomyosarcoma of the thyroid, for a total of 20 cases. Included in the category of CATT are all the thyroid tumors presenting clinically with an anaplastic growth pattern. The cytomorphology of these tumors varied, but the giant- and spindle-cell pattern was predominant. An accurate cytodiagnosis was possible, as per cytohistologic correlation, in seven cases, while in one case histological material was not available for study. Medullary carcinoma of the thyroid (MCT) showed a mixed spindle-cell and round-cell population in eight cases and an entirely spindle-cell population in one case. All cases of MCT were correctly diagnosed on cytology, and amyloid could be demonstrated in the cytologic smears in three cases. The cases of NHL and leiomyosarcoma could also be correctly interpreted on cytology.