On the right, the artery degenerates and the nerve will loop around the subclavian. On the left, will loop around the aorta and ductus arteriosus. Left 5th arch artery becomes the pulmonary artery and ductus arteriosus. The right 5th arch artery becomes the pulmonary with degeneration of the rest of this arch vessel. Always lateral to the facial nerve.
Treatment is surgical excision.
Histopathology -Generally lined by stratified squamous epithelium that often contains keratin, hair follicles, sweat and sebaceous glands. Their scheme based on anatomy and not histology. I is a cyst or sinus or fistulous tract in the preauricular region and the tract courses lateral and superior to the facial nerve, parallels the EAC and terminated without an opening in the canal. II is below the mandible in the anteriosuperior neck. Tract courses superiorly over ramus of mandible and terminates at the bony cartilaginous junction at the EAC, either with or without direct communication.