Fig. 4

Histological findings of surgically resected specimens. a Endometrial lesion of the lower uterine segment. The tumor grew exophytically and invaded the muscular layer with tongue-like projections. b Prominent intravascular extension in the paraovarian connective tissue. c Oval tumor cells surround arterioles in a whorl-like pattern. d In some areas, tumor cells have abundant clear cytoplasm and show an epithelioid appearance. e Foci of hypocellular fibrous areas show similarity to the lesions of the pre-operative transvaginal resections. f, g, and h Immunohistochemical staining of the surgically resected tumor. f Estrogen receptor. The tumor cells are diffusely positive with weak to moderate signal intensity. g Progesterone receptor. The tumor cells are diffusely and strongly positive. h Cluster of differentiation 10. The tumor cells are diffusely positive