Pleomorphic Adenoma of External Auditory Canal

IntroductionPleomorphic adenoma (PA) is the most common benign tumor of the major salivary glands. It may also arise from minor salivary glands of the upper aerodigestive tract. PA of the auditory canal is a rarity. The earlier hypothesis that PA of the auditory canal originates from ectopic salivary gland tissue has not yet been proven. Currently it is assumed that PA of the external auditory canal originates from the myoepithelia of the local ceruminal glands. The tumor is accordingly classified by the WHO as a ceruminal adenoma. The tendency to recurrence and malignant transformation known from PA of the salivary glands has also been described for PA of the auditory canal.

Case reportAn 81-year-old patient complained of a left-sided increase of bilateral pre-existing hearing loss for several weeks. On the microscopy of the ear the left auditory canal was almost completely closed by a smooth, rough protrusion of the auditory canal floor. The pure-tone audiogram showed a sensorineural hearing loss on the right and a combined hearing loss on the left. Computed tomography of the petrous bone revealed a 5 mm soft tissue formation without bony destruction obstructing the left auditory canal. The tumor was completely resected by transmeatal approach in general anesthesia. Histological work-up revealed a diagnosis of PA. Six weeks after surgery the ear canal appeared completely re-epithelialised and wide.

ConclusionsPA is a very rare but important differential diagnosis of tumors of the external auditory canal because of potential malignant transformation. Therapy consists of complete excision with long-term follow-up because of the risk of recurrence.

Publikationsverlauf

Artikel online veröffentlicht:
24. Mai 2022