Abstract

Thymofibrolipoma is an extremely rare tumor in the anterior mediastinum, and represents a histologic variant of the usual thymolipoma. Herein, we report a case of thymofibrolipoma in a 9-year-old girl who had a huge mass with fatty attenuation in the right hemithorax on chest computed tomography. She denied any subjective symptoms except mild fever. The surgically resected tumor was ovoid, soft and well-encapsulated, measuring 9.0 x 7.5 x 7.0 cm. The cut surface was light tan in color with yellowish streaks. Microscopically, two distinct areas were admixed in different proportions. One consisted of normal thymic tissue with subinvoluted features and the other was composed of extensive areas of collagenous tissue interspersed in mature adipose tissue. In a high power view, there were thin strands of remnant thymic epithelial cells, separating the pseudolobules. Thymofibrolipoma should be distinguished from other benign or malignant conditions, occurring in the anterior mediastinum, so that unnecessary treatment can be avoided.

• Keywords: Mediastinal neoplasms;Thymofibrolipoma