Perivascular epithelioid cell tumor (PEComa) of the uterus: Challenges of pregnancy in determining prognosis and optimal treatment

•PEComas are rare mesenchymal neoplasms with malignant potential.•Diagnosis is difficult to make by imaging or symptoms alone.•Diagnosis should prompt referral to a gynecologic oncologist to determine appropriate treatment strategy.•Biopsy is warranted when abnormal findings are encountered during a surgery. Perivascular epithelioid cell tumor (PEComa) is a rare mesenchymal neoplasm that exhibits immunohistochemical evidence of smooth muscle and melanocytic differentiation. Case: We report a case of uterine PEComa in a 21 year-old primigravida, presenting at time of c-section as a small subserosal lesion that expressed soft tan-brown tissue fragments. Microscopically the cells were epithelioid, staining positive for TFE3 and HMB45. Significant cytologic atypia and mitotic activity were concerning for malignancy. The patient was treated post-partum with total robotic hysterectomy and right salpingo-oopherectomy, and is currently without evidence of disease. This case of PEComa diagnosed during pregnancy highlights the importance of intra-operative biopsy and the difficulty of predicting malignant potential of PEComa in the setting of a gravid uterus with a dynamic smooth muscle architecture.