Fistulas of the first branchial cleft are relatively rare and are caused by remnants of the branchial cleft during differentiation or by inadequate closure. Among these, ectodermal lesions originating from the first branchial groove have been reported more frequently, while endodermal lesions originating from the first branchial pouch have been reported less frequently. We report a case in which an upper auricular fistula associated with microtia was found to be connected to the middle ear cavity. The fistula was considered to be a first branchial groove- and first branchial pouch-derived fistula, which is extremely rare, based on the fistula being in contact with the middle ear cavity as well as the histopathological findings of stratified squamous epithelium of ectodermal origin and ciliated columnar epithelium of endodermal origin.
