Fine-needle aspiration cytology of epidermoid cyst of the thyroid: report of a case and review of seven cases.

The cytological and histological features of a case of epidermoid cyst of thyroid are reported. Unlike the more common intrathyroid branchial cleft cyst, this lesion does not contain any lymphoid tissue. The presence of scattered small groups of smooth muscle fibers in the periepithelial fibrous tissue in this case suggests a teratomatous histogenesis.