Correlation between the pathology and clinical presentations in patients with adenoid cystic carcinoma of the external auditory canal.

The solid subtype presents the worst prognosis, and is prone to perineural invasion. Despite frequently occurring in ACC of the external auditory canal, perineural invasion may not be associated with otalgia. In ACC of the external auditory canal, high rates of occult parotid involvement support adjunctive superficial parotidectomy.