Epithelioid angiomyolipoma: a rare renal tumor with histopathological complexity

Renal angiomyolipomas (AMLs) are rare benign kidney tumors. Epithelioid angiomyolipoma (EAML) is a distinct variant with unique histopathological features and recognized malignant potential. This study highlights the diagnostic features and pitfalls of EAML. A 41-year-old woman was referred after an incidental left renal mass was detected on ultrasound. She was asymptomatic, with unremarkable examination and laboratory results, though her family history included several malignancies. Magnetic resonance imaging revealed a 3.5-cm partly exophytic, posterior lower-pole renal mass without pelvicalyceal invasion. The patient underwent robotic-assisted left partial nephrectomy. Histopathology showed a tumor composed predominantly of epithelioid cells with reduced vascularity, thick-walled vessels, and adipose tissue. Immunohistochemistry demonstrated positivity for smooth muscle actin (SMA) and Human Melanoma Black-45 (HMB-45) and negativity for Paired box 8 (PAX-8), confirming EAML. EAML poses diagnostic and management challenges due to uncertain malignant potential and lack of guidelines. Surgical resection remains primary treatment, with long-term surveillance recommended.