External auditory canal cholesteatoma: a rare entity.
Cholesteatomas are cystic masses lined with stratified keratinizing squamous epithelium. Most are found in the epitympanum of the middle ear cavity; only rarely do they occur in the external auditory canal external auditory canal
See ear canal. . (1) The differential diagnosis of an external auditory canal cholesteatoma (EACC) includes keratosis keratosis /ker·a·to·sis/ (ker?ah-to´sis) pl. kerato´ses any horny growth, such as a wart or callosity.keratot´ic
actinic keratosis obturans, postinflammatory medial canal fibrosis, malignant otitis externa malignant otitis externa ENT Otitis externa accompanied by osteomyelitis and bone erosion. See Otitis externa. , and squamous cell carcinoma squamous cell carcinoma
A carcinoma that arises from squamous epithelium and is the most common form of skin cancer. Also called cancroid, epidermoid carcinoma. .
EACC can occur spontaneously following trauma or surgery as a result of the entrapment of squamous epithelial debris during the healing process. Normally, epithelial migration carries debris outward from the tympanic membrane. However, when debris has accumulated in the external auditory canal, changes in cellular proliferation may occur, and they can evolve into an EACC. (1)
Clinically, patients tend to present with otorrhea and a chronic, dull pain. The otorrhea is believed to be linked to an associated localized infection, usually a Pseudomonas aeruginosa infection. (1,2) Less commonly, patients present with a conductive hearing loss Conductive hearing loss
A type of medically treatable hearing loss in which the inner ear is usually normal, but there are specific problems in the middle or outer ears that prevent sound from getting to the inner ear in a normal way. that is caused by occlusion of the external canal by the debris or the cholesteatoma. (3)
On otoscopic examination, EACC can be difficult to distinguish from other inflammatory, infectious, or neoplastic processes. Keratosis obturans is the most difficult to distinguish, and since EACC may require surgical intervention and keratosis obturans is managed medically, distinguishing between these entities is important.
The characteristic imaging features of an EACC are the appearance of a soft-tissue mass and associated erosion of the inferior portion of the external canal with a localized periostitis periostitis /peri·os·ti·tis/ (-os-ti´tis) inflammation of the periosteum.
per·i·os·ti·tis or per·i·os·te·i·tis
Inflammation of the periosteum. and sequestration of bone (figure). (2) Bone fragments are often present within the mass, but the tympanic membrane is typically spared. Occasionally, an EACC extends into the middle ear cavity, facial nerve canal, mastoid cavity, or tegmen tegmen /teg·men/ (teg´men) pl. teg´mina [L.] a covering structure or roof.
tegmen tym´pani tympani. (4) It is believed that the bone erosion, periostitis, and sequestration are the results of a weakening of the bone by proteolytic enzymes within the cyst lining. (l) In addition, the erosion might also be partly related to the accumulation of keratin debris, which traps moisture and results in a bacterial infection that can cause ulceration of the epithelial layer and the formation of granulation tissue.
Treatment options include conservative medical therapy with frequent cleaning and debridement of the keratin debris and sequestered bone. If the mastoid air cells are invaded, a modified radical mastoidectomy modified radical mastoidectomy ENT An operation to eradicate disease of the middle ear cavity and mastoid process, in which the mastoid and epitympanic spaces are converted into an easily accessible common cavity by removing the posterior and superior external may be indicated, with the tympanic membrane and ossicles Ossicles
The three small bones of the middle ear: the malleus (hammer), the incus (anvil) and the stapes (stirrup). These bones help carry sound from the eardrum to the inner ear.
Mentioned in: Otitis Media, Stapedectomy left intact. (1)
(1.) Heilbrun ME, Salzman KL, Glastonbury CM, et al. External auditory canal cholesteatoma: Clinical and imaging spectrum. AJNR Am J Neuroradiol 2003;24:751-6.
(2.) Malcolm PN, Francis IS, Wareing MJ, Cox TC. CT appearances of external ear canal cholesteatoma. Br J Radiol 1997;70:959-60.
(3.) Naim R, Linthicum FH Jr. External auditory canal cholesteatoma. Otol Neurotol 2004;25:412-13.
(4.) Chakeres DW, Kapila A, LaMasters D. Soft-tissue abnormalities of the external auditory canal: Subject review of CT findings. Radiology 1985; 156:105-9.
Matthew Dang, MD; Enrique Palacios, MD