Papillary thyroid carcinoma with nodular fasciitis-like stroma: a usual entity with distinctive morphology.

Papillary thyroid carcinoma (PTC) is a common malignancy with multiple variants, some of which are rarely encountered in routine surgical pathology practice. PTC with exuberant nodular fasciitis-like stroma (PTC-NFS) or PTC with fibromatosis-like stroma (PTC-FMS) is one such variant. We report a case of PTC-NFS, a tumor characterized by an abundant stromal component with an intervening epithelial component with the typical morphologic features of conventional PTC. We review the literature on this rare variant, discuss the importance of a thorough search for epithelial components within any fibroproliferative lesion of the thyroid, and address the diagnostic difficulties created by the tumor's extensive stromal component.