Epithelioid hemangioendothelioma is a vascular tumor of endothelial origin with an intermediate histological and clinical behavior somewhere between that of hemangiomas and angiosarcomas.1 Its incidence is very low, and its most frequent location is at the hepatic and pulmonary level.2–4 Its localization in the mediastinum is exceptional, and diagnosis is usually established after surgical treatment.

Our patient is a 56-year-old woman with no medical history of interest who was sent to our consultation with the suspicion of a teratoma after thoracic CT performed due to pain in the right hemithorax. The CT scan revealed a 4-cm mass with fatty density and calcium in its interior located in the mediastinum. Thoracic MRI identified a 4-cm mass in the right anterior mediastinum with intralesional fatty foci and foci of hyposignal in related with calcifications. The mass was in contact with the brachiocephalic artery and with the right subclavian vein with no clear data of invasion (Fig. 1a). By means of transverse cervicotomy, we proceeded with the exeresis of the mass. Post-operative evolution was satisfactory. The histologic report of the piece described a 5cm×4cm mass with different mesenchymal components: mature-looking adipose tissue, fibroblastic fusiform cells, bone tissue with thick trabeculas in anarchic distribution and numerous capillary vessels covered with epithelioid endothelium (Fig. 1b). The epithelioid cells showed an endothelial immunophenotype (CD 31 and CD 34 +). These findings supported the diagnosis of epithelioid hemangioendothelioma with an extensive metaplastic ossification. This result was confirmed by the Pathological Anatomy Department at Brigham and Women's Hospital in Boston (USA), reference center for the study of soft tissue tumors.

Fig. 1.

(a) Thoracic MRI where the mass is observed at the anterior mediastinal level; (b) macroscopic image of the resected mass. It is a nodular formation, measuring 5cm×4cm×3.6cm with a smooth surface and areas of brown-violet coloration.

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Epithelioid hemangioendothelioma usually presents in patients around the age of 40; the presentation is asymptomatic and is usually a coincidental radiological finding in half of patients.5 In our case, the radiological suspicion was for a teratoma due to the calcifications observed on the imaging studies. Although its most frequent localization is at the hepatic and pulmonary level, other localizations have been reported in the mediastinum.5 The histologic diagnosis with routine techniques is difficult, and it is necessary on the majority of occasions to use immunohistochemical techniques. In our case, we observed a large metaplastic ossification with positive epithelioid cells in the immunohistochemical study for CD 31 and CD 34, which coincides with the series by Suster et al. confirming the vascular origin of this type of tumor.5 As for prognosis and treatment, we should mention that it is a tumor with slow growth. The treatment of choice is surgical extirpation.