Clinical and pathological features of renal epithelioid angiomyolipoma (PEComa): A single institution series.

Renal angiomyolipomas are benign tumors of the kidney that belong to the 'PEComa: perivascular epithelioid cell' family. Epithelioid AMLs (eAML) are a rare monotypic subtype with malignant potential, that can occur sporadically or be associated with tuberous sclerosis (TSC). Due to their epithelioid nature, eAMLs can closely resemble high-grade renal cell carcinoma (RCC), which may result in misdiagnosis. Multiple clinicopathologic parameters are predictive of worse outcomes for patients with eAML. Those can be used to stratify patients into groups with low, intermediate and high risk for disease progression. A high index of suspicion and a thorough immunohistochemical study are required to correctly diagnose eAML. Radiographically, eAMLs are also a diagnostic challenge as they share features with RCC on CT and MR imaging. Due to this close mimicry, the true incidence of eAML is thought to be much higher than 200 cases as reported in the literature. We report a series of four patients diagnosed with eAML and compare their clinical courses. We also report on the successful treatment of a patient with pulmonary metastasis from eAML using the mTOR inhibitor, everolimus. By identifying eAML and recognizing its high-risk features, it is possible mTOR inhibitors may have a meaningful role in the adjuvant treatment of these patients.