Abstract
BACKGROUND: Thymolipoma is a rare benign tumor arising from the anterior mediastinal thymus and is composed of mature fatty tissue and interspersed nonneoplastic thymic tissue. This tumor accounts for only a small percentage of mediastinal masses, and the majority of them are asymptomatic and found incidentally. To date, fewer than 200 cases have been published in the world literature, of which most excised tumors weighed less than 0.5 kg and the largest weighed 6 kg. CASE SUMMARY: A 23-year-old man presented with a complaint of progressive breathlessness for 6 mo. His forced vital capacity was only 23.6% of the predicted capacity, and his arterial partial pressure of oxygen and carbon dioxide were 51 and 60 mmHg, respectively, without oxygen inhalation. Chest computed tomography revealed a large fat-containing mass in the anterior mediastinum that measured 26 cm × 20 cm × 30 cm in size and occupied most of the thoracic cavity. Percutaneous mass biopsy revealed only thymic tissue without signs of malignancy. A right posterolateral thoracotomy was successfully performed to remove the tumor along with the capsule, and the excised tumor weighed 7.5 kg, which to our knowledge, was the largest surgically removed tumor of thymic origin. Postoperatively, the patient's shortness of breath was resolved, and the histopathological diagnosis was thymolipoma. No signs of recurrence were observed at the 6-mo follow-up. CONCLUSION: Giant thymolipoma causing respiratory failure is rare and dangerous. Despite the high risks, surgical resection is feasible and effective.