Lipofibroadenoma of the thymus: a case report
© Qu et al.; licensee BioMed Central Ltd. 2013
Received: 26 February 2013
Accepted: 29 June 2013
Published: 15 July 2013
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.
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Lipofibroadenoma (LFA), a thymic tumor, was classified into “rare thymomas” in the WHO classification . Until now, one and only case of LFA was reported in the English literature , in which a 62-year old man was suffered from dyspnea, dizziness and pure red cell aplasia. The tumor was found in the anterior mediastinum by Chest X-ray scan and diagnosed as LFA with thymoma type B1. Here we report another case of LFA, which is not accompanied with any type of thymoma. The clinical and pathological features are presented.
Using immunohistochemical staining, the epithelial strands of the tumor were positive for AE1/AE3 and CK19 (Figure 3C), and the lymphocytes were immunostained with CD3 and CD20 (Figure 3D). The Ki67 labeling index was also calculated to be approximately less than 1%. Based on histological features and immunohistochemical characters, a diagnosis of LFA of the thymus was made, and the total follow-up period was determined to be forty-six months. The repeated X-ray scan revealed no recurring or residual lesion was found during the post-surgical course.
Previously reported cases of lipofibroadenoma of the thymus
Accompanied with PRCA
Accompanied with other thymoma
Kuo T et al. 
Dyspnea and dizziness
Yes, Accompanied with B1-type thymoma
Pathology is still the gold standard in the diagnosis of LFA, in which the classic histological features were with thymic epithelial cells arranged as crack structure under the background of fibrous tissue. Lymphocytes are infiltrated in the crack and fat cells are distributed as individual or groups. In rare case, thymic corpuscle could be found. As far as the present case is concerned, the typical morphological characteristics are observed under the low power. Epithelial cells were positive to AE1/AE3, CK19 and the lymphocytes were immunostained with CD3 and CD20, which were used to make the diagnosis of LFA.
The differential diagnosis of LFA in histology primarily separated into thymolipoma and fibroadenoma, which intraductal type composed of interstitial and epithelial component. Epithelial cells were arranged as crack under the fibrous element, and the lack of fat cells and thymic component could be helpful in the distinguishing diagnosis. Thymolipoma was an unusual thymoma, which could lead to myasthenia gravis and autoimmune dysfunction . Recent report suggested that thymolipoma origined from thymic true hyperplasia . Under the microscope, epithelial and fibrous components can not be observed in the thymolipoma, which was the important point distinguishing from LFA. In addition, the biomarkers of CD57, c-Jun, p73, Casp9, and N-ras are also useful in the differential diagnosis [5, 6].
The treatment for the patient we presented was thymectomy, and the necessary follow-up examination among forty-six months disclosed there was no palindromic lesion. RJ et al. had ever reported that COX-2 was expressed in all subtypes of thymomas and thymic carcinomas , which indicated COX-2 might be another potential novel target beside in thymic tumor therapeutic areas.
In general, LFA was a rare and benign thymic tumor, which might not be related to pure red cell aplasia, and the tumor accompanied with or without any type of thymoma. Histological features and immunohistochemical staining played an important role in diagnosis and differential diagnosis, in which thymolipoma and fibroadenoma were primary differential diagnosis. Thymectomy was regarded as the best treatment. However, much more cases are needed for further research.
Written informed consent was obtained from the patient for publication of this case report and any accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal.
We would like to thank Dr. Hongbo Wang in Yantai University for helping in correcting language errors in our manuscript.
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