Cytopathology of high-grade papillary thyroid carcinomas: tall-cell variant, diffuse sclerosing variant, and poorly differentiated papillary carcinoma.

Cytologic reports of the aggressive tall-cell and diffuse sclerosing variants of papillary carcinoma have emphasized features such as tall and large cells, increased nuclear size, nuclear pleomorphism, intranuclear pseudoinclusions, three-dimensional tissue fragments, squamous-like cells, and dense inflammatory background as characteristic features. However, the specificity of these features in identifying the particular variants and distinguishing them from other poorly differentiated papillary carcinomas and typical low-grade forms of papillary carcinoma has not been established. The objective of this study was to assess the predictive value of these reported cytologic features. Fourteen cases of high-grade papillary carcinoma consisting of the aggressive variants (tall-cell variant (tcv) and diffuse sclerosing variant (dsv)) and poorly differentiated papillary carcinomas (pdpc) were compared to 18 cases of low-grade papillary carcinoma. Seven cytologic features consisting of the presence of tall and large cells, architectural disorganization, nuclear enlargement, prominent intranuclear pseudoinclusions, nuclear pleomorphism, lymphocytic infiltrate, and squamoid appearance of the neoplastic cells were evaluated. Cytology samples from tcv, dsv, and pdpc consistently demonstrated 3 of the 7 cytologic features (architectural disorganization, nuclear enlargement, and pleomorphism). In contrast, only two of the samples from low-grade cases demonstrated these 3 features. The recognition of these 3 cytologic features had a positive predictive value of 88% and a negative predictive value of 100% for identifying tcv, dsv, and pdpc. The remaining cytologic features were not a consistent feature in the variants, and by cytology alone, distinction between the aggressive variants (dsv and tcv) and pdpc could not be made.