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Case Reports
. 2022 Dec 16:7:19.
doi: 10.21037/med-22-32. eCollection 2023.

Asymptomatic lipofibroadenoma in a 17-year-old male: a case report and literature review of a rare entity

Michael A den Bakker  1   2 , Marijn A Vermeulen  3 , Cornelis P van de Ven  3 , Simone A J Ter Horst  3   4 , Lennart Kester  3 , Ronald R de Krijger  3   5
Affiliations
Case Reports

Asymptomatic lipofibroadenoma in a 17-year-old male: a case report and literature review of a rare entity

Michael A den Bakker et al. Mediastinum. .

Abstract

Background: The most common thymic tumours, thymomas, are derived from thymic epithelium and are generally low-grade neoplasm. Frankly malignant tumours, thymic carcinomas are rarer still. Exceedingly rare thymic tumours contain a mesenchymal tissue component such as fibrous connective tissue and/or mature fat. Lipofibroadenoma (LFA) is a very rare mixed epithelial-mesenchymal thymic tumour, included in the category of thymic epithelial tumors. LFA in addition to a mature adipocytic component, contains variable epithelial and mesenchymal tissue components. Owing to the presence of an epithelial component in LFA, this entity, in contrast to thymolipoma, is included in the World Health Organization (WHO) category of thymic epithelial neoplasm. Currently only 12 LFA cases have been described. The 12 previously reported cases all behaved in a benign fashion, although four cases were associated with a conventional type of thymoma. We here present a new, 13th, case of LFA.

Case description: The LFA was discovered incidentally in a previously healthy 17-year-old male after investigations for suspected pneumonia. On imaging a mass was discovered in the anterior mediastinum which was subsequently surgically removed. The resected tumour was extensively investigated, including the first instance of full molecular analysis of this rare entity and all available literature on LFA was sourced to provide a comprehensive overview. The histology of this LFA was similar to previously described cases. No gene mutations or rearrangements were identified. The patient made an uneventful recovery and after 13 months of follow-up remained well.

Conclusions: An additional, 13th case of LFA is presented. Based on the available literature it appears that LFA may be considered a benign composite thymic tumour, although the combination of an additional conventional thymoma component may warrant closer follow-up.

Keywords: Mediastinum; case report; thymoma; thymus.

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Conflict of interest statement

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://med.amegroups.com/article/view/10.21037/med-22-32/coif). MAdB serves as an unpaid editorial board member of Mediastinum from March 2022 to February 2024. The other authors have no conflicts of interest to declare.

Figures

Figure 1
Figure 1
MRI and CT-scan. (A) Post-contrast T1 vibe (volumetric interpolated breath-hold examination) fat saturated sagittal MR-image, depicting a supra-cardial fatty mass (indicated by arrows). (B) Contrast-enhanced transverse CT-image showing the left para-cardial located low density mass (indicated by arrows). MRI, magnetic resonance imaging; CT, computed tomography; MR, magnetic resonance.
Figure 2
Figure 2
Gross image of resected tumour. (A) Thinly encapsulated 12.5 cm excised tumour. (B) On sectioning a predominantly fatty specimen is seen with focally grey fibrous areas.
Figure 3
Figure 3
Histology. (A) Fibro-fatty tissue with ramifying cords of epithelial cells. Mature fatty tissue, present in several areas in this slide (a single area indicated by *). Pink fibrous collagenous tissue is indicated (#). Darker branching strands of epithelial cells ramify through both fibrous and fatty tissue. (B) Scattered small calcifications were present, again note the slender strands of epithelial cells. (C) Discrete collections of spindled epithelial cells, comparable to those of a spindle cell thymoma. (D) Lymphoid component with a Hassall’s corpuscle. HE stained sections (A,B: low power view; C,D: medium power view). HE, hematoxylin-eosin.
Figure 4
Figure 4
Immunohistochemistry. The epithelial strands are highlighted in the AE1/AE3 cytokeratin (A) and p63 (B) stains (medium power views). The lymphoid component shows a mixed B-cell (CD20 positive) population (C) combined with an immature (TdT positive) T-cell population (D) (medium power views).
See this image and copyright information in PMC

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