Novel detection of the CAMTA1-WWTR1 fusion gene in extra-adrenal myelolipoma-like lesion: a case report

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.