Papillary thyroid carcinoma with fibromatosis-like or nodular fasciitis-like stroma is a very rare variant. There was a 8 cm, well delinated grayish-white nodular lesion, which measured 12x7x5 cm, on the cut-surface of the bilateral total thyroidectomy material of the 37-year-old woman. Microscopically the tumor was largely composed of uniform spindle cells without significant atypia with long fascicles or fibromxyoid stroma without organization, and there were papillary carcioma areas composed of papillary and follicular components with classical nuclear features. There were rare mitosis within stromal spindle cells. Immunohistochemically stromal cells were positive for vimentin and smooth muscle actin. There were no staining with desmin, S-100, CD34 and pancytokeratin. Morphological and immunohistochemical features have suggested that stromal cells may be of myofibroblastic origin. In this paper the histogenesis of stromal cells of the papillary thyroid carcinoma with fibromatosis/nodular fasciitis-like stroma, and the lesions within the differential diagnosis of this tumor are evaluated.