Treatment of an invasive thymoma-like left innominate venous aneurysm using allogeneic pericardium with continuous horizontal mattress sutures: a case report.

Background: Left innominate vein aneurysm (LIVA) is a rare condition with an unclear cause. Only a few cases of this entity have been reported, and standard therapeutic guidelines for its diagnosis and treatment have not yet been established. There is no consensus about the optimal surgical access, thoracotomy may be the preferred method of treatment. Case Description: A 55-year-old male who was tentatively diagnosed with invasive thymoma via thoracic computed tomography (CT) was ultimately diagnosed with left innominate venous aneurysm via contrast-enhanced thoracic CT. The patient was asymptomatic. He was operated through a median sternotomy. A saccular left innominate venous aneurysm was discovered intraoperatively, and instead of reconstruction with a vascular graft or cardiopulmonary bypass (CPB), it was treated with allogeneic pericardium placed with continuous horizontal mattress sutures and sternotomy closure. The procedure was successful, with no major bleeding event; to our knowledge, this is the first reported use of allogeneic pericardium with continuous horizontal mattress sutures for this condition. The postoperative course and follow-up were unremarkable, with no need for anticoagulant therapy and no evidence of recurrence observed at the 1-year follow-up. Conclusions: Left innominate venous aneurysm is easily misdiagnosed as invasive thymoma and can be definitively diagnosed via enhanced thoracic CT examination or magnetic resonance imaging (MRI). This novel approach may offer valuable insights for guiding future therapeutic strategies.