Two Cases of Ectopic Hamartomatous Thymoma Masquerading as Sarcoma.

Takahito Kondo,Hiroyuki Yonekawa,Wataru Shimbashi,Hiroki Mitani,Hiroko Tanaka,Yukiko Sato,Hirofumi Fukushima,Toru Sasaki,Kazuyoshi Kawabata

doi:10.1155/2017/1672919

Takahito Kondo, Hiroyuki Yonekawa + Show 7 more

Open Access

https://doi.org/10.1155/2017/1672919

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Abstract

Ectopic hamartomatous thymoma (EHT) is an extremely rare benign tumor. EHTs are difficult to differentiate from sarcomas, especially synovial sarcomas. We encountered two cases of EHT that were referred from other hospitals because sarcoma was suspected. In these cases, fusion gene detection via polymerase chain reaction or fluorescence in situ hybridization was useful for differentiating EHT from synovial sarcoma. EHT requires accurate diagnosis before surgery to avoid excessive treatment. Both tumor location and the presence of fat inside the tumor are important imaging findings for EHT, and confirmation of spindle cells, epithelial cells, and mature adipose cells in the tumor is an important pathological finding. It is important to exclude synovial sarcoma from the differential diagnosis via fusion gene analysis.

Highlights

Ectopic hamartomatous thymoma (EHT) is a benign tumor that occurs with extreme rarity in the lower neck
We report two cases of EHT in whom the differentiation of EHT from synovial sarcoma (SS) was assisted by fusion gene detection using polymerase chain reaction (PCR) or fluorescence in situ hybridization (FISH), as genetic diagnostic techniques [2]
On histopathological examination of the resected tumor, the tumor consisted of plump to thin spindle cells growing in a bundle shape (Figure 4(a)) and adipose cells (Figure 4(b))

Summary

Introduction

Ectopic hamartomatous thymoma (EHT) is a benign tumor that occurs with extreme rarity in the lower neck. EHT disease is referred to as a thymoma, there is no evidence of thymic origin or differentiation [1]. Because EHT is an extremely rare tumor, it is often difficult to diagnose. EHT is difficult to differentiate from synovial sarcoma (SS) or other malignant tumors. If EHT is diagnosed incorrectly, treatment leads to unnecessary resection. We report two cases of EHT in whom the differentiation of EHT from SS was assisted by fusion gene detection using polymerase chain reaction (PCR) or fluorescence in situ hybridization (FISH), as genetic diagnostic techniques [2]

Case Presentation

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Discussion