Uterine PEComa With Lymphangioleiomyomatosis (LAM)-Like Features: A Case Report.

Perivascular epithelioid cell tumors (PEComas) of the uterus are rare mesenchymal neoplasms characterized by myogenic and melanocytic differentiation. These tumors can mimic other uterine mesenchymal tumors in their clinical presentation and morphology. We report a case of a 58-year-old woman who presented with abnormal uterine bleeding. Initial imaging revealed an endometrial polyp, which was later diagnosed as a leiomyoma on excision biopsy. A subsequent hysterectomy with bilateral salpingectomy revealed a uterine neoplasm composed of spindled to epithelioid cells with low-grade cytologic atypia, infiltrative edges, and extensive lymphovascular invasions, initially suggestive of low-grade endometrial stromal sarcoma. However, immunohistochemical stains demonstrated tumor positivity for HMB45, desmin, and Cathepsin K, and genetic testing revealed a TSC1 variant, leading to a definite diagnosis of uterine PEComa with lymphangioleiomyomatosis (LAM)-like features. The patient's postoperative course was uneventful, and follow-up imaging showed no evidence of metastatic disease. This case highlights the importance of integrated morphological, immunohistochemical, and molecular assessment in differentiating uterine mesenchymal neoplasms to guide appropriate clinical management.