Dermoid cyst of the maxillary sinus.

Dermoid cysts are rare developmental teratomatous lesions composed of ectodermally derived stratified squamous epithelium and mesodermally derived skin adnexal structures. As part of the teratomatous lesion group, dermoid cysts are related to teratoid cysts, true teratomas, and epignathi. Although several theories have been postulated, the pathogenesis of dermoid cysts, and teratomatous lesions in general, is unclear. Most commonly affecting sites within the head and neck, dermoid cysts may be found in the frontotemporal/lateral brow area, central nasal area, oral cavity, lateral neck, and other sites. We present what is believed to be the first reported case arising within the maxillary sinus and briefly discuss the possible pathogenesis.