Follicular variant of papillary carcinoma of the thyroid. A cytologic study of 15 cases.

Objective: To study the cytologic findings of follicular variant of papillary thyroid carcinoma (FVPTC) and to compare them with the cytologic findings on other thyroid lesions.
Study Design: The study group consisted of aspirate smears from 15 cases of histologically proven FVPTC. The control group consisted of 152 cases, including adenomatous colloid goiter (70), usual papillary carcinoma (40), follicular adenoma (30), Hürthle cell neoplasm (7) and medullary carcinoma (5).
Results: The smears of FVPTC revealed numerous colloid balls in the background, multilayered microfollicles (rosettes), numerous nuclear grooves and inclusions in the monolayer sheets of follicular cells, very rare giant cells, absence of calcification and papillary clusters. Rosettelike microfollicles and numerous colloid balls were not seen in the control group.
Conclusion: The combination of numerous colloid balls and rosettelike microfollicles was frequently seen in FVPTC. This combination was not observed in the control group.