TFE3 nuclear expression as a novel biomarker of ovarian sclerosing stromal tumors and associated with its histological morphology

Sclerosing stromal tumors of the ovary are benign and tend to occur in youthful women with lobular structures at low frequencies. Three types of cells, including luteinized cells, short spindle myoid cells, and intermediate cells, are found in the lobules which abundant in the blood vessels. Currently, immunohistochemistry is used to detect normal follicles, sclerosing stromal tumors, granulosa cell tumors, and fibromas/thecomas. Our research results showed that transcription factor enhancer 3 (TFE3) was moderate to strong positive in the theca interna layer of normal follicles. TFE3 was expressed in seven out of eight sclerosing stromal tumors, mainly in luteinized cells. It did not express in 20 granulosa cell tumors. Of the nine fibromas/thecomas, TFE3 was weakly staining in 2 cases and negative in the remaining 7 cases. The expression of TFE3 was also weak in only one microcystic stromal tumor. 8 cases of sclerosing stromal tumors were analyzed by FISH using a TFE3 separation probe, and the results were negative. In short, as a nuclear transcription protein, TFE3 specifically expressed in sclerosing stromal tumors and could serve as a new marker for the diagnosis and differential diagnosis of sclerosing stromal tumors. Moreover, we speculate that TFE3 will promotes the formation of the vascular plexus after entry into the nucleus, which can further explain why sclerosing stromal tumors are different from other ovary sex-cord stromal tumors.