Thymofibrolipoma: a case report and review of the literature

Thymofibrolipoma has been described as a variant of thymolipoma. To date, 3 cases have been reported, and the lesion have been described to consist of extensive areas of collagenous tissue interspersed with islands of mature adipose tissue and strands of thymic tissue.

A 43-year-old woman had an anterior mediastinal tumor. Macroscopically, the cut surface of the tumor was composed of a yellowish lipomatous component and a uniform whitish fibrous component with elastic stiffness. Microscopically, the tumor was composed of collagenous fibrous tissue with sparse spindle cells, mature adipocytes and strands or islands of thymic tissue. The spindle cells in the fibrous tissue had monoallelic deletion of the 13q14 region and corresponding loss of RB1 and FOXO1A protein expression.

This case report may strengthen the hypothesis that thymofibrolipoma is a neoplastic lesion and a variant of thymolipoma and that thymofibrolipoma and lipofibroadenoma are different names for the same lesion. The name "lipofibroadenoma" was given to the lesion because of its histological resemblance to fibroadenoma of the mammary gland. However, this name does not reflect the pathogenesis of this lesion, and the name "thymofibrolipoma" would be preferable. It will be necessary to discuss whether lipofibroadenoma should be listed as an independent entity in the WHO classification.