Perivascular epithelioid cell neoplasm (PEComa) harboring TFE3 gene rearrangements in a patient with Lynch syndrome.

A 38-year-old male with a history of Lynch syndrome was diagnosed with a rectal mucinous adenocarcinoma 6 years earlier. In the follow-up a pelvic nodule radiologically suggestive of a lymph node recurrence was found, and was surgically removed. Histopathological studies were suggestive of PEComa. Immunohistochemical studies showed diffuse positivity for HMB45 and TFE3, with scattered cells expressing MELAN A and actin. TFE3 gene rearrangement was confirmed with fluorescence in situ hybridization. Intact nuclear expression was observed for MLH1, MSH2, MSH6 and PMS2, and genetic studies confirmed microsatellite stability, arguing against a relation with Lynch syndrome. After 29 months, the patient remains alive with no evidence of recurrence of either the adenocarcinoma or the PEComa. Although some sarcomas have been described in Lynch syndrome families, cumulative evidence suggests that Lynch syndrome patients might also develop non-Lynch syndrome tumors. To the best of our knowledge, this is the first report of a PEComa in a patient with Lynch syndrome. TFE3-rearranged PEComas are a recently described variant defined by the translocation of TFE3, the features of which are poorly defined. This tumor adds to the list of sporadic non-Lynch syndrome-related tumors, and to the data of TFE3 rearrangement-associated PEComas.