AB005. Resection of an epithelioid hemangioendothelioma arising from the superior vena cava: a case report

Background: The incidence of mediastinal epithelial hemangioendothelioma is extremely rare. The treatment principles are not well established, but surgical resection with negative margins seems to yield the best prognosis.

Case Description: A 65-year-old male patient referred to our Thoracic Surgery Unit with a chest radiograph finding of right mediastinal shadow through routine physical examination. The patient denied any uncomfortable symptoms. The patient took physical examination regularly, a right mediastinal shadow was found in the former chest radiograph two years ago. The chest computed tomography (CT) revealed a right prevascular mediastinal mass of 5.8 cm × 5.7 cm, invaded into superior vena cava (SVC), with calcification and heterogeneous enhancement. The chest magnetic resonance imaging (MRI) suggested a mediastinal vascular neoplasm arising from SVC, with low signals on T1-weighted imaging and high signals on T2-weighted imaging, and heterogeneous enhancement. The serum tumor marker tests, including carcinoembryonic antigen (CEA), Cyfra 21-1, squamous cell carcinoma (SCC) antigen, neuron-specific enolase (NSE), and cancer antigen 125 (CA125), alpha-fetoprotein (AFP) and β-human chorionic gonadotropin (β-HCG) were negative. The patient received a core needle biopsy was performed in another hospital, and the pathological review suggested epithelial hemangioendothelioma in Shanghai Chest Hospital. A median sternotomy surgery was performed. The bilateral pleural space was entered and the mass was found to be arising from SVC. The phrenic nerve was stretched over and inseparable from the tumor, and ultimately resected en bloc. The tumor invaded to pericardium which was partially resected. An artificial reconstruction between left innominate vein (LIV) and right atrial appendage was performed. The tumor and invaded structures were resected en bloc. The patient recovered uneventfully and was discharged from the hospital on the seventh day postoperatively. Pathology confirmed a 9 cm × 7 cm × 5 cm tumor with negative margins, and invasion into pericardium, LIV and SVC. Histologic examination demonstrated giant cells with part of myxoid stroma, staining positive for CD31, ERG and CD34. The gene test showed 50% positive for CAMTA1, consistent with epithelial hemangioendothelioma. There was no evidence of recurrence after a 40-month follow-up.

Conclusions: Mediastinal epithelial hemangioendothelioma is a rare malignant vascular tumor, which is often incidentally diagnosed. Complete resection of the tumor arising from SVC with careful preoperative planning could be achieved and was important for prognosis.

Keywords: Epithelioid hemangioendothelioma; mediastinal neoplasm; case report