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

Background: The purpose of this study was to analyze the correlation between the pathology and clinical presentations in patients with adenoid cystic carcinoma (ACC) of the external auditory canal. Methods: Twenty-nine patients with ACC of the external auditory canal who underwent surgery were retrospectively reviewed. Results: Fifty percent of patients with solid pattern disease had recurrences, followed by those with cribriform (33%) and tubular (0%) pattern. Perineural invasion was common (55%), and occurred most frequently in the solid subtype (67%). The rate of otalgia was less in patients with perineural invasion (31% vs 46%). Most tumors (59%) involved the parotid gland, but it was not seen on preoperative MRI (35%). Conclusion: 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.