A case of TFE-3-positive non-neoplastic pseudodecidualized endometrium presenting as a cervical mass

Introduction/Objective TFE-3 gene encodes a transcription factor that promotes the expression of genes involved in cell growth and proliferation. Its overactivation can result in oncogenic activity. Although TFE-3 seems to be almost universally expressed in normal tissues, this expression should be at very low levels and strong nuclear expression of TFE-3 is seen almost exclusively in tumors containing or lacking the TFE-3 gene fusion. These include renal cell carcinoma, alveolar soft part sarcomas, epithelioid hemangioendotheliomas, PEComas, granular cell tumour, solid pseudopapillary neoplasm of the pancreas, and ovarian sclerosing stromal tumors. It must be emphasized that only nuclear expression of TFE-3 is of diagnostic value, as non-specific cytoplasmic staining is common. Methods/Case Report A 30-year-old woman with pelvic pain, heavy vaginal bleeding and ureteral stricture on oral contraceptive pill was found to have a cervical mass on exam. Cervical biopsy showed fragments of benign squamous epithelium and polypoid endometrial tissue with atrophic glandular component, stromal pseudodecidualization and abundant mixed inflammation. The stroma was positive for CD10, and negative for P16, desmin, cytokeratin ae1/ae3, CD34, calretinin. There was patchy moderate to strong nuclear staining for TFE-3 (Anti-TFE-3 rabbit monoclonal primary antibody, Cell MarqueTM). No evidence of a neoplastic process was seen, and the overall findings fit with either prolapsed endometrial tissue or endometriosis. TFE-3 by FISH showed no rearrangement of the TFE-3 gene region, ruling out alveolar soft part sarcoma. Results (if a Case Study enter NA) NA Conclusion The Human Protein Atlas, a program mapping all the human proteins in cells and tissues, shows that endometrial stromal and glandular cells can have moderate TFE-3 nuclear expression, using Anti-TFE-3 rabbit polyclonal antibody (Prestige Antibodies ®). In our case, focal strong expression was seen using a monoclonal antibody. In the pathology literature this finding has not been previously reported. Pathologists should be aware of the possibility of strong nuclear expression of TFE-3 in non-neoplastic endometrium to avoid potential misdiagnosis.