epithelioid hemangioendothelioma is a rare vascular neoplasm , considered to have clinical behavior intermediate between a benign hemangioma and malignant angiosarcoma . , these tumors often arise from a medium - to - large - caliber vein , most commonly in the extremities . symptoms of these tumors vary depending on location , and can present with extremity swelling , pain , cough or dyspnea . complete surgical excision of these tumors is advocated given their potential for malignant degeneration and metastasis . a 17-year - old male presented with complaints of left - arm swelling and occasional pain . imaging obtained of the chest and neck revealed a large anterior mediastinal mass involving the major venous structures of the left chest ( fig .  1 ) . computed tomography ( ct)-guided needle biopsy was performed , with inconclusive results , and this was followed by a left video - assisted thoracoscopic surgery ( vats ) procedure yielding enough tissue for formal diagnosis of an epithelioid hemangioendothelioma . after extensive multidisciplinary consultation and preoperative planning , the patient was taken to the operating room for a median sternotomy , thymectomy and en - bloc excision of the tumor and vessels ( fig .  2 ) . vascular reconstruction of the left brachiocephalic and left subclavian vein was performed with an 8 mm ringed polytetrafluoroethylene graft , with an additional end - to - side anastomosis of the left internal jugular vein to the graft . the patient tolerated the initial procedure well , was extubated on postoperative day 1 and advanced to an oral diet . after several days , large - volume milky drainage from the chest tube was evaluated and presence of a chyle leak confirmed . the patient returned to the operating room on postoperative day 6 for a right vats with ligation of the thoracic duct . final tumor measurements were 7.5  5.5  3.5 cm , and final pathology confirmed an epithelioid hemangioendothelioma with no mitoses , < 5% necrosis and a final pathologic staging of pt2b . figure  1:computed tomography demonstrating a mass in the left chest involving the brachiocephalic vein . figure  2:intraoperative photography demonstrating the epithelioid hemangioendothelioma encasing the left brachiocephalic vein , left internal jugular vein , and left subclavian vein . intraoperative photography demonstrating the epithelioid hemangioendothelioma encasing the left brachiocephalic vein , left internal jugular vein , and left subclavian vein . malignant degeneration and metastases are reported to occur in 25% of patients , with death occurring in up to 15% of patients . despite the indolent clinical course , the potential for tumor advancement mandates complete surgical excision . the vascular involvement necessitates meticulous preoperative planning and multidisciplinary approach for aggressive resection and concomitant reconstruction of involved vessels . in this case , the surgical team included cardiothoracic surgeons , vascular surgeons and a pediatric surgeon .
epithelioid hemangioendotheliomas are rare vascular tumors , often arising from medium to large veins in the extremities 
 . symptoms of these tumors vary depending upon location . 
 rarely , tumors may arise in chest and involve large vessels in the mediastinum . 
 we present a case of a 17-year - old male presenting with compressive symptoms of the left upper extremity who was found to have a large epithelioid hemangioendothelioma encasing the left brachiocephalic vein .