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Epithelioid Angioleiomyoma Mimicking Metastatic Melanoma in a Liver Tumor.

It is well known to pathologists that melanoma is "the great mimicker", looking like almost any other tumor, and able to metastasize anywhere in the body. We report a case of a 48-year-old female with a history metastatic melanoma 4years before, presented with a hepatic mass. Microscopic examination of the liver mass revealed sheets of pleomorphic, epithelioid cells, which expressed a pan-melanocytic cocktail (MART1, HMB45 and tyrosinase). These findings were initially interpreted as metastatic melanoma and the case was transferred for dermatopathology consultation. We compared the morphology of this tumor to the primary melanoma and noticed that the primary melanoma showed nevoid cytology, morphologically distinct from the liver lesion. Consequently, we performed additional immunohistochemical studies, which determined that the liver mass was negative for S100 and SOX10, and established a final diagnosis of epithelioid angiomyolipoma. The key for reaching the correct diagnosis was the morphology comparison with the original lesion and the evaluation of a wider immunohistochemical profile. For appropriate management in patients with new lesions, even in the context of a patient with known metastatic disease, it is essential to consider other neoplasms in the differential diagnosis. This article is protected by copyright. All rights reserved.