Two Cases of Ectopic Hamartomatous Thymoma Masquerading as Sarcoma.
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.
Department of Head and Neck Oncology, Cancer Institute Hospital of Japanese Foundation for Cancer Research, 3-8-31 Ariake, Koutou-ku, Tokyo 135-8550, Japan.
Takahito
0000-0003-0590-7907
T
Kondo
Department of Pathology, Cancer Institute Hospital of Japanese Foundation for Cancer Research, 3-8-31 Ariake, Koutou-ku, Tokyo 135-8550, Japan.
Yukiko
Y
Sato
Department of Diagnostic Imaging, Cancer Institute Hospital of Japanese Foundation for Cancer Research, 3-8-31 Ariake, Koutou-ku, Tokyo 135-8550, Japan.
Hiroko
H
Tanaka
Department of Head and Neck Oncology, Cancer Institute Hospital of Japanese Foundation for Cancer Research, 3-8-31 Ariake, Koutou-ku, Tokyo 135-8550, Japan.
Toru
T
Sasaki
Department of Head and Neck Oncology, Cancer Institute Hospital of Japanese Foundation for Cancer Research, 3-8-31 Ariake, Koutou-ku, Tokyo 135-8550, Japan.
Kazuyoshi
K
Kawabata
Department of Head and Neck Oncology, Cancer Institute Hospital of Japanese Foundation for Cancer Research, 3-8-31 Ariake, Koutou-ku, Tokyo 135-8550, Japan.
Hiroki
H
Mitani
Department of Head and Neck Oncology, Cancer Institute Hospital of Japanese Foundation for Cancer Research, 3-8-31 Ariake, Koutou-ku, Tokyo 135-8550, Japan.
Hiroyuki
H
Yonekawa
Department of Head and Neck Oncology, Cancer Institute Hospital of Japanese Foundation for Cancer Research, 3-8-31 Ariake, Koutou-ku, Tokyo 135-8550, Japan.
Hirofumi
H
Fukushima
Department of Head and Neck Oncology, Cancer Institute Hospital of Japanese Foundation for Cancer Research, 3-8-31 Ariake, Koutou-ku, Tokyo 135-8550, Japan.
Wataru
W
Shimbashi