前頸部に瘻孔を有した側頸部皮様嚢胞の1例

Dermoid Cyst of the Lateral Neck with Anterior Neck Fistula

　はじめに

　皮様嚢胞が周辺への瘻孔形成を伴うことは稀といわれている^1）。また，皮様嚢胞は頭頸部領域では正中線上，特に口腔底に出現することが多く，側頸部に出現することは少ない^2〜4）。今回われわれは，前頸部皮膚瘻孔を有する側頸部皮様嚢胞の1例を経験したので報告する。

Dermoid cyst of the lateral neck with cutaneous fistula of the anterior neck is rare, because the majority of the head and neck dermoid cysts occur in the midline. A 54-year-old man was complaining of an anterior neck fistula and discharge since childhood. Small fistula was found in the anterior neck skin on the surface of the thyroid cartilage. CT scan revealed that the subcutaneous fistula was ascending on the surface of the lateral alar of the thyroid cartilage and cystic dilatation wasidentified, moreover this fistula seemed to be ascending to the right submandibular region between the mylohyoid muscle and hyoglossus muscle. Pre-operative diagnosis was thyroglossal duct cyst with fistula or dermoid cyst with fistula, however, these cyst and fistula were unrelated to the hyoid bone in operative finding. Histopath-ological examination revealed dermoid cyst.

Though this dermoid cyst presented in the lateral neck at the height of the hyoid bone, its descending fistula was opened in the midline and ascending tract was observed toward midline of the oral floor. From these findings, it was supposed that the lateral dermoid cyst originated in the midline which had been a residual of the epithelial tissue entrapped during the midline fusion of the first and/or second branchial arches, but shifted its position laterally during its expansion.