Microscopic examination and immunohistochemical stains. A) The ovarian parenchyma is occupied by a thyroid type neoplasm. Note the follicles. (HE 40×). B) Massive extension of the neoplasm in the parenchyma. There is no evidence of benign struma ovary or others components of teratoma (HE 40×). C) Follicular and papillary components of neoplasm (HE 100×). D) Papillary component of neoplasm. Papillae are lined by cells with ground glass nuclei. There are also some mitoses (HE 400×). E) Positive reaction of thyroglobulin antibody (HE 400×). F) Nuclear positive reaction of TTF-1 antibody (HE 100×).