Epithelioid hemangioendothelioma - an unexpected diagnosis of a mediastinal tumor with extensive local thrombosis.

Epithelioid hemangioendothelioma (EHE) is a rare vascular tumor and the mediastinal localization is amongst the most infrequent. We present the case of a 37-year-old woman with a history of resected left thyroid tumor that presented to our department for evaluation of a left supraclavicular palpable mass in close contact with local vascular structures, and with heterogeneous contrast enhancement as described by computed tomography (CT) and magnetic resonance imaging (MRI). Considering the history of the patient, the presumptive diagnosis of thyroid tumor recurrence was established, and the patient was referred to surgical department. During procedure, we encountered important bleeding from a ruptured jugular vein branch, which we assumed to be a newly formed tumor blood vessel. After surgery (48 hours postoperatively), the patient developed important local thrombosis that encompassed the left internal jugular vein, left subclavian vein and the left brachiocephalic trunk that partially subsided after anticoagulant therapy. The histological examination revealed the presence of a vascular tumor proliferation of epithelioid endothelial cells that was characteristic of an EHE confirmed later on the immunohistochemical studies as Yes-associated protein 1-transcription factor E3 (YAP1-TFE3) subtype. In addition to the case report, some relevant information from the scarce literature data about mediastinal EHE were reviewed here.