サイログロブリンの免疫染色により確定診断がなされた右側頸部原発甲状舌管癌の1例

Thyroglossal Duct Carcinoma in the Lateral Neck Confirmed by Immunohistological Stain of Thyroglobulin:Report of a Case

　はじめに

　甲状舌管嚢胞および鰓溝性嚢胞は先天性頸部腫瘤の大半を占め，ごくまれに悪性化するが，両者の発生部位的特異性などから鑑別診断は比較的容易と考えられている^1〜3）。最近，著者らは，解剖学的発生部位などから鰓溝性嚢胞癌を強く考えたが，1）組織学的に甲状腺癌類似の乳頭状腺癌であること，および2）免疫組織学的に嚢胞壁上皮と癌細胞の両方にサイログロブリンが証明されることから甲状舌管癌と診断したまれな1例を経験したので報告する。

Thyroglossal duct cyst and branchial cleft cyst are the two most common congenital cysts of the neck, and rarely show malignant change. The diag-nosis is made based on the location of the cyst as well as the histological findings. We reported athyroglossal duct carcinoma which was originally considered as branchial cleft carcinoma because of its location. A diagnosis of papillary adenocar-cinoma of the thyroid gland was once made by the histological examinations, but the immunohis-tological examination revealed thyroglobulin identified both in the epithelium of the cystic wall and tumor cells. This finding suggested that im-munohistological identification of thyroglobulin is important to differentiate thyroglossal duct car-cinoma from branchial cleft carcinoma.