Ovarian perivascular epithelioid cell tumor not otherwise specified with transcription factor E3 gene rearrangement: a case report and review of the literature.

We report the first case of isolated ovarian perivascular epithelioid cell tumor not otherwise specified in a 33-year-old woman with no history of tuberous sclerosis. A right ovary specimen revealed a well-circumscribed 2.5 × 2 cm solid mass. Microscopically, the mass was composed of nests of tumor cells that were separated by fibrous septa. The tumor cells were composed of pure epithelioid cells with abundant clear cytoplasm and dark brown pigments. Immunohistochemically, the tumor cells showed diffuse and strong cytoplasmic staining of HMB45; however, the tumor cells were not reactive for smooth muscle actin, desmin, inhibin-α, calretinin, and carcinoembryonic antigen. Strong nuclear expression of transcription factor E3 protein was observed in most tumor cells, and transcription factor E3 fluorescence in situ hybridization showed transcription factor E3 rearrangements associated with balanced Xp11 translocations.