Papillary thyroid carcinoma with nodular fasciitis-like stroma. Pitfalls in fine-needle aspiration cytology.

Papillary thyroid carcinoma with nodular fasciitis-like stroma is one of the rare variants of papillary thyroid carcinoma. The problems posed by the exuberant nodular fasciitis-like stroma, which obscures the neoplastic nature of the tumor, are recognized in surgical pathology but have received little attention in the cytopathology literature. We report a rare case of papillary thyroid carcinoma in which nodular fasciitis-like stroma posed difficulty on fine-needle aspiration cytology. The differential diagnosis of fibroproliferative processes in thyroid fine-needle aspirations is also discussed.