Abstract
BACKGROUND: Thymic mucosa-associated lymphoid tissue (MALT) lymphoma is rare and is known to be associated with Sjögren's syndrome (SjS). SjS is rarely accompanied by serositis. Here, we describe the first case of postoperative cardiac tamponade and acute pleuritis in a patient with thymic MALT lymphoma associated with SjS. CASE PRESENTATION: A 33-year-old woman with SjS presented with an anterior mediastinal mass on chest computed tomography, which was performed for further examination of the condition. Suspecting a thymic MALT lymphoma or thymic epithelial tumor, total thymectomy was performed. The mediastinal mass was histopathologically diagnosed as a thymic MALT lymphoma. The patient was discharged with a good postoperative course but visited the hospital 30 days after surgery for dyspnea. Cardiac tamponade was observed and drainage was performed. Four days after pericardial drainage, chest radiography revealed massive left pleural effusion, and thoracic drainage was performed. The patient was diagnosed with serositis associated with SjS and treated with methylprednisolone, which relieved cardiac tamponade and pleuritis. CONCLUSIONS: Surgical invasion of thymic MALT lymphomas associated with SjS may cause serositis. Postoperative follow-up should be conducted, considering the possibility of cardiac tamponade or acute pleuritis due to serositis as postoperative complications.