External auditory canal cholesteatoma, also known as keratosis obturans of the external auditory canal, is accumulated desquamated epithelium containing cholesterol crystals that blocks the bony portion of the external auditory canal. Its histological structure is the same as that of middle ear cholesteatoma, but often mixed with cerumen debris.
Etiology
Etiology is unknown, but may be associated with the active growth of basal cells in the local skin germinal layer and abnormal increase in the shedding of keratinized epithelial cells resulting from chronic congestion caused by the long-term stimulation of various lesions such as cerumen impaction, inflammation, foreign bodies, and fungal infection. If migration is blocked, they accumulate in the external auditory canal; the center gradually decay, decompose, and degenerate, producing cholesterol crystals, thereby forming cholesteatoma.
Clinical manifestations
The disease occurs mostly in adults, predominantly unilateral, but also bilateral. Typical external auditory canal cholesteatoma is formed at the bottom of the external auditory canal, and is manifested by local sequestrum formation. Small cholesteatoma without secondary infection may have no apparent symptoms. Large cholesteatoma can cause aural fullness, tinnitus, and hearing deterioration. In case of secondary infection, there may be otalgia, headache, and foul-smelling secretions in the external auditory canal. Examination shows that the deep part of the external auditory canal is blocked by white or yellow cholesteatoma, wrapped by multiple layers of scales. After the large cholesteatoma is removed, the bones of the external auditory canal are destroyed and resorbed, and the bony portion of the external auditory canal is significantly enlarged. The tympanic membrane is intact and may be congested and retracted. Huge external auditory canal cholesteatoma can destroy the posterior wall of the external auditory canal and invade the middle ear, widely destroy the mastoid bone, and can cause mastoiditis and peripheral facial paralysis.
Figure 1 The cholesteatoma in the left external auditory canal damaging the posterior wall of the external auditory canal
Figure 2 Cholesteatoma in the external auditory canal
Diagnosis
A diagnosis can be readily established based on the medical history and the characteristic white cholesteatoma in the external auditory canal. Pathological examination can confirm the diagnosis. Attention should be paid to the differentiation from primary middle ear cholesteatoma, external auditory canal cancer, and necrotizing external otitis. Temporal bone CT or mastoid x-ray can be performed if necessary.
Treatment
Cholesteatoma without concurrent infection can easily be removed, and can be removed with a cerumen hook.
When concurrent infection occurs, attention should be paid to infection control. However, it is difficult to quickly control the infection alone. Only after the cholesteatoma is completely or partially removed, can the inflammation subside.
In patients with severe infection or irremovable cholesteatoma, general anesthesia and surgical microscopy can be considered, and systemic antibiotics should be administered to control the infection. Postoperative observation is needed, and residual or regenerated cholesteatoma should be removed.
In case of extensive lesion, canalplasty may be required, and sometimes even mastoidectomy is required.