Thyroid tumors: cytomorphology of papillary carcinoma.

Of 2,012 fine-needle aspirations (FNA) of the thyroid performed by the authors between the years 1984 and 1988, a detailed cytomorphologic analysis of 95 cases diagnosed as neoplastic on histology and/or cytology and those that received an equivocal cytodiagnosis is presented. Discussed are papillary carcinomas (28 correctly diagnosed on FNA and two false positives). In most of the cases of papillary carcinoma, the cytologic features were characteristic enough to enable accurate tumor typing. Follicular cells with dense cytoplasm, well defined cell margins, and presence of papillary clusters were the most consistent features observed. Intranuclear cytoplasmic inclusions, though characteristic, were found in only 66.6% of cases. In cystic papillary carcinomas (seven cases) study of the cyst wall as well as the cyst contents enabled an accurate cytodiagnosis. Two cases of multinodular goiter with papillary hyperplasia could not be distinguished with certainty from papillary carcinoma on cytologic grounds.