Surgical treatment of a rare case of epithelioid hemangioendothelioma of the azygos vein

Abstract

Epithelioid hemangioendothelioma (EHE) of soft tissues is a rare low-grade vascular tumour, with variable malignancy. Mediastinal localization is exceptional. We report the first case of a radically resected EHE of the azygos vein (AV). A 47-year old man presented to our institution with an asymptomatic incidental neck-chest computerized tomography (CT) evidence of a 3 cm mediastinal mass, resembling a station 4R lymphadenopathy, with rather distinct margins, strictly adjacent to the AV. (18)F-fluorodeoxyglucose positron emission tomography (FDG-PET)/CT revealed a SUV max of 2.3. Fiberbronchoscopy with EBUS-trans-tracheal needle aspiration of station 4R yielded nondiagnostic cytology result. A right lateral thoracotomy revealed an ovoidal mediastinal mass originating from the AV, unresectable from it but showing cleavage from the superior vena cava. The mass with the involved AV was resected en bloc by vascular stapler. Histopathology revealed a venous EHE arising from the AV. For the low mitotic rate and small tumour size, no adjuvant therapy was administered. Total body CT scan at one year from surgery shows neither local recurrence, nor distant metastases. EHE should be considered in the differential diagnosis of mediastinal masses in adult patients. After radical removal prognosis is generally favourable, but strict follow-up must be performed because aggressive forms have been described.

Figure 1:

(a) Chest CT scan showing a suspected mediastinal station 4R lymphadenopathy (mass indicated by arrow), 3 cm in diameter, with dishomogeneous structure, rather distinct margins, but not sure cleavage from the SVC, strictly adjacent to the azygos vein (AV); (b, c) ¹⁸F-FDG-PET/CT showing a slightly increased uptake (SUV max 2.3) at the level of mediastinal station 4R lymph node; (d) CT scan at one year from surgery, showing a normal mediastinum without signs of recurrence.

Figure 2:

(a) Resected mediastinal mass, resembling a station 4R lymphadenopathy, although in reality originated from the AV, being unresectable from it, but showing cleavage from the SVC; the mass was isolated and resected en bloc with the involved tract of AV by Endo-GIA vascular stapler; (b) haematoxylin–eosin 10×: epithelioid hemangioendothelioma (EHE) arising from the AV (AV wall indicated by black arrow); (c, d) haematoxylin–eosin 200× and 400×: typical pattern of cords and nests of epithelioid endothelial cells in a myxohyaline stroma and the so-called ‘blister’ cells (for intracytoplasmic lumina).