Primary Branchiogenic Carcinoma.

Background: Primary branchiogenic carcinoma (BC) is an exceptional diagnostic entity. In most cases, suspicion of BC is confirmed to be a cystic lymph node metastasis of an occult primary tumor. Martin and Khafif therefore established diagnostic criteria, emphasizing above all the importance of a histologically assessed transformation of cystic lining epithelium into an invasive squamous cell carcinoma in one pathological lesion after the exclusion of a primary tumor.

Case Report: We present a case report of an 80-year-old patient who presented for a follow-up for an 8-year history of a benign lateral cervical cyst, which was not surgically treated due to the patients high risk of complications from general anesthesia. In spite of the risk, the surgery was performed after a sudden clinical progression, and surprisingly, post-operative histology revealed BC. Conslusion: BC is a very rare entity, strictly defined by Martins and Khafifs criteria. Recently, BCs have been presented in the literature only as unique case reports responding as in our patient to the above mentioned criteria, with particular emphasis on the histological aspect, imaging the cystic lining epithelium transforming into an invasive squamous cell carcinoma in one pathological lesion and a long history without evidence of primary tumor. Key words: branchiogenic carcinoma - lateral branchial neck cyst - occult carcinoma - metastasis of unknown primary origin.