A mediastinal mass was incidentally detected by chest X-ray in a 44-year-old man. Computed tomography findings revealed that the mass was a possible malignancy in the right and middle mediastinum and was removed by surgical resection. Macroscopically, the resected specimen was a well-demarcated yellowish, brownish, and whitish mass. Microscopically, a solid lesion with cords of epithelioid cells in the extra-adrenal myelolipoma-like lesion was observed. Immunohistochemically, the solid lesion was positive for typical vascular markers and CAMTA1, the expression of which is highly specific for epithelioid hemangioendothelioma (EHE). The endothelial cells and bone marrow elements of myelolipoma-like lesion were also positive for CAMTA1. Fluorescence in situ hybridization examination detected the CAMTA1-WWTR1 fusion gene not only in the solid lesion but also in the endothelial cells and bone marrow elements of myelolipoma-like lesion. To our knowledge, this is the first report suggesting common genetic abnormality, CAMTA1-WWTR1 fusion, in cases of EHE and extra-adrenal myelolipoma.

一名 44 岁男性的胸部 X 光检查偶然发现了纵隔肿块。计算机断层扫描结果显示，肿块可能是右侧和中纵隔的恶性肿瘤，并通过手术切除切除。宏观上，切除的标本是一个界限清楚的淡黄色、褐色和白色肿块。显微镜下，在肾上腺外骨髓脂肪瘤样病变中观察到具有上皮样细胞索的实性病变。免疫组化显示，实性病变对典型血管标志物和 CAMTA1 呈阳性，其表达对上皮样血管内皮瘤 (EHE) 具有高度特异性。骨髓脂肪瘤样病变的内皮细胞和骨髓成分也呈CAMTA1阳性。荧光原位杂交检测检测到CAMTA1-WWTR1融合基因不仅存在于实性病变中，而且存在于骨髓脂肪瘤样病变的内皮细胞和骨髓成分中。据我们所知，这是第一份关于 EHE 和肾上腺外骨髓脂肪瘤病例中常见的遗传异常（CAMTA1-WWTR1融合）的报告。