RESUMEN
A case of Clement and Scully's type II uterine tumor resembling ovarian sex cord tumors (UTROSCT) occurring in a 21-year-old woman is presented. Grossly, a 10 cm-sized fundic myometrial tumor, which was projecting into the endometrial cavity, was excised. Histologically, most parts of tumor showed the morphology of sex cord-like differentiation, including solid anastomosing cords or tubules, solid nests, and trabeculae arranged in a plexiform pattern. The sex cord elements were studied immunohistochemically with markers of sex cord, steroid cell differentiation (inhibin, O13, and A103), or both. The tumor cells were found to be diffusely immunoreactive for O13 (MIC2, CD99) and very focally positive for inhibin. There were also constant immunoreactivity for vimentin and hormone receptors and relatively rare positivity for desmin, actin, and cytokeratin. These findings provide strong evidence for the presence of true sex cord elements, the derivation of which seems to derive from the capacity for divergent differentiation of uterine stroma. This report demonstrates immunohistochemically true sex cord differentiation in UTROSCT.