Papillary carcinoma of the thyroid gland with nodular fasciitis-like stroma

Papillary thyroid carcinoma with nodular fasciitis-like stroma (PTC-NFS) is a rare variant of PTC. The term 'PTC with fibromatosis-like stroma' has been used as a synonym to describe this variant. It is characterized by extensive proliferation of fibroblasts and myofibroblasts in the tumor stroma, which occurs in up to 80% of the tumors. We herein describe a case of PTC-NFS which developed in a 49-year-old woman with the demonstration of findings of ultrasonography, fine needle aspiration cytology and histological examination of the lesion. To characterize the stromal components, we investigated the expression of several immunohistochemical markers which have been shown to be expressed differently in nodular fasciitis (NF) and fibromatosis (FM). The immunostaining results demonstrated nuclear and cytoplasmic accumulation of β-catenin, cytoplasmic transforming growth factor-β expression and nuclear Smad expression in the stromal cells, suggesting that the stromal cells in this case have similar molecular profiles to those of FM rather than NF.