[Lipofibroadenoma of the thymus]

Here we report a case of a rare thymic tumors histologically diagnosed as lipofibroadenoma. The patient was a 32-year-old male who displayed an anterior mediastinal tumor on a chest computed tomography (CT) scan while being treated for pneumonia. The tumor was localized within the thymus, and the diameter was 3 cm. No significant change was observed in the tumor on a CT scan taken 6 months after the 1st scan. Suspecting a thymoma from the CT and magnetic resonance imaging (MRI) findings, we performed a thymothymectomy via a median sternotomy. The histopathological diagnosis was a lipofibroadenoma of the thymus. The findings resembled fibroadenoma of the breast. Lymphocytes were scarce within the tumor with abundant interstitial stroma, and the tumor epithelial cells displayed restiform and dendritic structures. The epithelial cells were mostly negative for Ki-67 immunohistochemical staining. A very small amount of calcification was detected within the tumor using alizarin red staining. Based on the histopathological findings, it was considered to be a benign tumor with little growth potential, and which had been present for a long period of time.