Fig. 1.

Malignant struma ovarii presenting with follicular carcinoma. (A) There are multiple tumor nodules on the omentum. (B) The cut surface of the tumor is tan-colored and solid. (C) At low magnification, there are follicles of various sizes containing pink-colored colloid resembling thyroid follicular tumor. (D) At higher magnification, no nuclear features suggesting papillary carcinoma, nuclear groove, ground-glass appearance, and intranuclear cytoplasmic inclusion are observed. Immunohistochemically, tumor cells show diffuse positivity for PAX8 (E) and TTF-1 (F). Scattered p53 positive tumor cells showing a wild-type staining pattern (G). Nuclear accumulation of β-catenin is not observed. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)