ABSTRACT
Thyroid papillary carcinoma (TPC) with exuberant nodular fasciitis-like stroma is one of the rare variants of TPC. To date, only 19 cases have been reported in the English medical literature. We report here on the the first Korean case of TPC that contained a prominent nodular fasciitis-like stroma. A 40-year-old female presented with a hard painless right neck mass that had been present for two months. Total thyroidectomy disclosed a solitary nodule in the mid portion of the right lobe that measured 25 x 20 mm. The tumor was well delineated, but it was not encapsulated. Microscopically, the tumor was a typical papillary carcinoma except that large areas of the tumor were occupied by a stroma composed of irregular fascicular spindle cells. The stromal component accounted for 60% of the tumor mass. The spindle cells exhibited neither atypism nor mitosis, and the tumor's extensive stromal cell proliferation resembled the appearance of nodular fasciitis of the soft tissues. Immunohistochemically, the spindle cells were positive for vimentin and alpha-smooth muscle actin, but they were negative for thyroglobulin, thyroid transcription factor-1, S-100 protein, CD34 and desmin, and this represents myofibroblastic features.