Abstract
Metachronous occurrence of p16-negative branchiogenic carcinoma and p16-positive oropharyngeal carcinoma
Chiaki Nakahama＊, Kenta Uemura, Chieko Yokota, Nanami Nakajima, Takahiro Okuno, Kenichi Kohashi, Kishiko Sunami
＊Department of Otolaryngology and Head and Neck Surgery, Graduate School of Medicine, Osaka Metropolitan University, Osaka
We report a rare case of sequential squamous cell carcinomas with different HPV status. A 62-year-old man underwent resection of a cervical cystic lesion in 2020, diagnosed as p16-negative squamous cell carcinoma arising in a branchial cleft cyst. No primary site was detected, and malignant transformation of the cyst was suspected. In 2024, he developed cervical lymphadenopathy；neck dissection revealed p16-positive squamous cell carcinoma. Further evaluation identified a primary tumor in the left oropharyngeal wall, also p16-positive. This case highlights the diagnostic challenges of differentiating true branchiogenic carcinoma from HPV-related oropharyngeal carcinoma.
はじめに
側頸囊胞は第二鰓弓由来の良性囊胞性病変であり，成人発症例の一部には悪性転化を伴うことが報告されている。悪性転化はまれであり，多くは扁平上皮癌である。近年では，ヒトパピローマウイルス（HPV）感染に関連したp16陽性扁平上皮癌が中咽頭を中心に発生することが知られており，非HPV関連癌とは臨床的特徴や予後が異なる。本症例は，初発時にp16陰性の側頸囊胞悪性転化を認め，その後約3年を経てp16陽性中咽頭癌を発症したきわめてまれな経過を示したため，文献的考察を加えて報告する。