Branchial cyst carcinoma revisited: stem cells, dormancy and malignant transformation

Branchial cleft cysts are among the most common causes for a congenital neck mass. Branchial cleft cyst carcinoma (BCCC) is a type of cancer that arises from cells within these cysts. Despite the distinct criteria that have been reported for its diagnosis, BCCC remains a controversial entity. We report a case of type I, first BCCC, on a 71-year-old white man. The diagnosis was based on the proposed criteria following lesion history and location, surgical excision, histology, and panendoscopy. We argue for the first time the hypothesis that congenital branchial cysts and BCCC tumors may result from progenitor cell rests of the embryological branchial development. After a period of dormancy, these cells could eventually awake and proliferate, thus giving rise to branchial cleft cysts. With the acquirement of mutations due to genomic instability, some clones of these cells could transform to malignant stem cells, thus clinically manifesting as BCCC. The wide recognition of stem cells and their role in carcinogenesis provides a new context for the etiopathogenesis of controversial and rare entities such as the BCCC.