Carcinoma arising in a branchial cleft cyst.

A patient is presented who was found to have invasive squamous cell carcinoma arising in the epithelial lining of a lateral cervical cyst which had been present for more than 40 years. Radical neck dissection was performed, and metastases were found in a single cervical lymph node. A critical review of cases of branchiogenic carcinoma reported over the past quarter-century yielded no more than three others which meet the criteria for diagnosis of this entity established by Martin, Morfit, and Ehrlich in 1950.