Rare PEComa Tumors Show Promise for Targeted mTOR Inhibitor Therapy

This comprehensive review examines perivascular epithelioid cell tumors (PEComas), a rare family of mesenchymal tumors that can develop throughout the body. These tumors predominantly affect women and occur across various anatomical sites including reproductive organs, kidneys, liver, lungs, and soft tissues.

While most PEComas follow a benign clinical course, malignant variants exist and are characterized by larger tumor size, high mitotic rates, tissue necrosis, and nuclear abnormalities. The tumors express distinctive molecular markers including melanocytic proteins and muscle-specific antigens, which aid in diagnosis.

A significant finding is the identification of a TFE3-rearranged PEComa subtype that occurs independently of tuberous sclerosis complex mutations. These tumors show distinct features including younger patient age, unique cellular architecture, minimal muscle marker expression, and strong TFE3 protein presence.

Surgical resection remains the gold standard for treatment, but emerging evidence supports mTOR inhibitor therapy effectiveness. Clinical trials and case reports demonstrate promising results with these targeted agents, particularly valuable for patients with inoperable tumors or metastatic disease. Radiation therapy shows limited efficacy based on current evidence.