Lipofibroadenoma of the thymus: a case report

Abstract

We observed an unusual case of Lipofibroadenoma (LFA) in the anterior mediastinum with a 21-year-old man, who was detected with a mass on a chest X-ray scan for one month. Thymothymectomy was then performed and the mass was excised completely, in which the tumor was histologically composed of epithelial cells, lymphocytes, mature adipose and fibrous tissue. Within the tumor, the fat cells was distributed singly or multifocally under the ground of fibro tissue with hyaline degeneration, and the epithelial cells were arranged as crack structure with lymphocytes infiltrated sparsely. By immunohistochemical staining assay, the epithelial cells were positive for AE1/AE3 and CK19, and the lymphocytes were CD3 and CD20 positive. Based on the histological characters, a diagnosis of LFA was made, and the total follow-up period was determined to be forty six months. The final repeated CT scan revealed no recurring or residual lesions were detected during the post-surgical course.

Virtual slide: The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1500429801911703.

Figure 1

Imaging. Chest X-ray scan reveals a limited semicircle shadow located in the left heart edge.

Figure 2

Gross morphology of the tumor. The tumor is oval with clear margin. Cut surface gives a solid appearance, grey in color and hard in quality (top right corner).

Figure 3

Histological examination and immunohistochemical features of the tumor. (A) The tumor shows irregularly connected strands forms a “Dog-like” structure in a dense fibrous tissue with scattered individual or groups of fat cells (H&E staining, ×40). (B) Sparse lymphocytes are infiltrated in the slender elongate epithelial strands and in some area, thymic corpuscle can be observed (H&E staining, ×100). (C) The epithelial strands of the tumor are positive for CK19 (Envision×100). (D) Lymphocytes are immunostained by CD3 (Envision×100).