Malignant PEComa of the Uterus Mimicking Uterine Fibroids: An Elusive Diagnosis

Abstract

Aim: To present a rare case of malignant uterine perivascular epithelioid cell tumor (PEComa), highlighting diagnostic challenges and management strategies. Case Presentation: A 55-year-old woman presented with abnormal uterine bleeding (AUB) and ultrasound findings suggestive of uterine fibroids. Her symptoms persisted despite medical therapy, needing surgical intervention. Total abdominal hysterectomy with bilateral salpingo-oophorectomy revealed a uterine tumor with histopathological features characteristic of PEComa. Immunohistochemistry confirmed markers consistent with malignant PEComa, including HMB45 positivity. Based on the WHO and Folpe’s criteria, the tumor was classified as malignant. The disease was confined to the uterus, with clear surgical margins. Active surveillance was adopted and show no evidence of recurrence at follow-up. Discussion: Malignant uterine PEComa is an exceptionally rare neoplasm, often presenting with non-specific symptoms mimicking common uterine tumors. Preoperative diagnosis is difficult at present, hence diagnosis relies on histopathology and immunohistochemical evaluation. Surgery remains the cornerstone of treatment, as PEComas are resistant to chemoradiation. Role of adjuvant therapy remains unclear in early-stage disease, but mTOR inhibitors show promising results in advanced or recurrent cases. Disease confined to the uterus with clear margins is associated with a favorable prognosis. Active surveillance with scheduled follow up and imaging is recommended given its highly variable clinical courses. Conclusion: This case underscores the importance of considering rare entities when standard treatments fail. Early surgical intervention and comprehensive histopathological and immunohistochemical evaluation are critical for accurate diagnosis and management.