Abstract 12754: The Forgotten Circulation: Lymphovascular Malformation Presenting as a Complex Mediastinal Mass in a Young Adult

Abstract

A 20-year-old transgender male presented with one week of intermittent shortness of breath and chest pain. He reported dizziness and increasing pain when playing the trumpet. His exam was unremarkable, but chest X-ray showed mediastinal widening and opacification of the retrosternal space (Fig. 1A). Chest CT showed a well-defined centrally enhancing prevascular mediastinal mass abutting the superior vena cava (SVC) and right heart (Fig. 1B). He was referred to a thoracic surgeon for evaluation. Subsequent chest CT venography and MRI demonstrated a progressively enhancing, part-solid and cystic mass with dilated veins draining into the SVC and a phlebolith. Due to imaging and clinical features, including a low probability of malignancy given negative tumor markers, lymphovascular malformation was favored over other possibilities such as thymoma, germ cell tumor, sarcoma, or Kaposiform hemangioendothelioma. After multidisciplinary discussions between cardiology, radiology, cardiothoracic and pediatric surgery, and a review at a dedicated vascular anomalies center, the consensus was for close surveillance. A 6-week follow-up MRI showed no significant change, but given increased dyspnea and chest pain, the decision was made to proceed with surgical resection via median sternotomy. The tumor was densely adherent to the right phrenic nerve, pericardium, and SVC but was excised completely without complications (Fig. 1C). Pathology confirmed a benign vascular malformation with lymphatic and venous components (Fig 1D). This diagnosis is more common in the pediatric population but a rare cause of dyspnea and chest pain in a young adult. This case illustrates the value of multimodality imaging and multidisciplinary collaboration among adult and pediatric subspecialists in the diagnosis and treatment of a rare, complex mediastinal mass in a young adult patient.