512 Primary Renal Epithelioid Hemangioendothelioma Found at Autopsy: A Case Report and Literature Review

Introduction/Objective Epithelioid hemangioendothelioma (EHE) is a rare vascular tumor which can arise anywhere. Clinical presentation is variable. Some are asymptomatic, while others may cause pain or weight loss. Primary renal EHE is exceptionally rare and, to our knowledge, has been reported <10 times in the literature. Methods/Case Report A 59-year-old male was transferred from an outside hospital with suspected acute liver failure which progressed to multi-organ failure. He subsequently passed away. Autopsy revealed a firm well-circumscribed dark nodule (0.5 x 0.5 cm) in the left kidney. Microscopy of the nodule revealed epithelioid cells with eosinophilic cytoplasm and cytoplasmic vacuoles organized in strands and cords within a myxohyaline stroma. Some cells possessed cytoplasmic vacuoles containing erythrocytes. Similar cells were found in the heart and skin. Immunohistochemistry showed CAMTA1 negativity, TFE3 positivity, and supported vascular differentiation. Fluorescent in-situ hybridization was negative for WWTR1-CAMTA1 fusion and TFE3 rearrangement. Given the overall findings with the kidney possessing the largest and only grossly visible lesion, and that only microscopic lesions were seen in the heart and skin, a diagnosis of primary renal EHE was rendered. Results NA Conclusion The exceptional rarity, variable clinical presentation, and evolving molecular signature of primary renal EHE can lead to under recognition.