Abstract
Introduction: Thymolipoma is a rare benign neoplasm of the anterior mediastinum accounting for 2%-9% of thymic tumors. It mainly consists of adipose tissue comporting foci of thymic tissue. Neoplastic transformation of the epithelial component is extremely rare with four cases of thymoma and a case of thymic carcinoid previously reported.
Aim: To report a case of thymolipoma associated with B3 thymoma.
Case presentation: A 59 year-old woman treated for asthma presented with dyspnea. No mysthenia gravis was present. Imaging revealed a huge mediastinal tumor of fat density compressing the right lung. Surgical resection revealed a 2.8 kg and 39 cm tumor of mainly lipomatous aspect comporting a stellar solid focus of 3 cm. Microscopically, the tumor was a thymolipoma, with a focus (3 cm) of a B3 thymoma. No complementary treatment was applied and the patient is disease-free, two months after operation.
Conclusion: This is the first case of a B3 thymoma arising inside a giant thymolipoma. Diagnosis of thymolipoma should be suspected in a fat-density tumor of the anterior mediastinum. Malignant transformation despite rare is possible and resection is mandatory.
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