P3.CR-31 A Case of Thymoma with Autoimmune Hepatitis Following Preoperative Chemotherapy

Abstract

We encountered a case of thymoma with autoimmune hepatitis. A 63-year-old woman was found to have an abnormal finding on chest radiography during a medical checkup, but did not seek further care. She was referred to our hospital one year later when a bilateral hilar abnormality was again found during a checkup. Chest computed tomography (CT) showed a 4.6 × 3.0 × 5.6 cm mass with calcifications in the anterior mediastinum. The tumor invaded the right lung and middle lobe, in association with a 2.0-cm daughter nodule in the head of the main tumor, with multiple pleural seeding lesions in the right thoracic cavity. Although she was asymptomatic, the anti-acetylcholine receptor antibody level was elevated to 33 nmol/L and the soluble IL-2 receptor antibody was elevated to 1,700 U/mL. The mass was diagnosed with CT-guided biopsy as a type-B2 thymic tumor (cT3N0M1a, c-Stage IV). She underwent induction chemotherapy (ADOC, 2 courses). After chemotherapy, abnormal liver enzyme levels (aspartate aminotransferase: 451 U/L, alanine aminotransferase: 529 U/L) were noted on preoperative examination. She was diagnosed with autoimmune hepatitis based on liver biopsy findings and treated with oral prednisolone 30 mg. Surgery was performed after prednisolone dose was gradually decreased to 20 mg. Extended thymectomy and pulmonary wedge resection using median sternotomy were performed. Pleural dissemination was resected using video-assisted thoracoscopic surgery. The pathological findings showed type-B3 thymic carcinoma (pT3N0M1a, p-Stage IV, Masaoka classification IVa). She was placed under observation without any additional treatment. Prednisolone dose has been gradually decreased to 15 mg without exacerbation of liver function. The anti-acetylcholine receptor antibody level decreased after surgery. Autoimmune diseases in association with thymoma are well known, but reports of autoimmune hepatitis are very rare. Autoimmune hepatitis must be considered when acute liver damage is observed.