Epithelioid Angiomyolipoma Masquerading as Renal Cell Carcinoma: A Case Report.

Epithelioid angiomyolipoma (EAML) is a rare variant of angiomyolipoma with malignant behavior characterized by predominantly epithelioid cells and minimal fat, mimicking renal cell carcinoma (RCC) on imaging. Preoperative diagnosis is challenging due to its non-specific clinical and radiological features, necessitating a histopathological examination for accurate diagnosis. Unlike classic angiomyolipoma, EAML can demonstrate aggressive behavior, including local invasion, recurrence, and distant metastasis. Owing to the rarity of the tumor, there is a paucity of data regarding the immunohistochemical markers and molecular profiles for predicting biomarkers in EAML. We report a case of renal EAML in a 23-year-old female with liver and lymph node metastases, which was preoperatively diagnosed as RCC. Histopathological examination and immunohistochemistry favored a diagnosis of EAML. Furthermore, next-generation sequencing confirmed aTFE3 rearrangement with an SFPQ fusion. However, TFE3 immunopositivity was also noted in our case, serving as a potential pitfall by raising suspicion for TFE3-rearranged RCC. Therefore, this case highlights the importance of a comprehensive evaluation integrating morphology, immunohistochemistry, and molecular studies for accurate diagnosis.