INTRODUCTION Granulomatous inflammation is a distinctive ...

Cholesteatoma has been recognized for decades as a destructive lesion of the skull base that can
erode and destroy important structures within the temporal bone. Its capacity for CNS
complications (e.g. brain abscess, meningitis) makes it a potentially fatal lesion. The term
cholesteatoma is actually a misnomer since the lesion is not a neoplasm and does not contain
cholesterol (Ferlito, 1993).
A cholesteatoma consists of squamous epithelium that is trapped in the skull base. Squamous
epithelium trapped within the temporal bone, middle ear, or mastoid can expand only at the
expense of the bone that surrounds and contains it. Consequently, the complications associated
with a growing cholesteatoma include the possible injury to any of the structures normally found
within the temporal bone. Occasionally, cholesteatoma will escape the confines of the temporal
bone and skull base. Extratemporal complications may occur in the neck and/or the CNS.
Cholesteatoma sometimes will reach sufficient size within the cranium, so as to distort normal
brain and produce mass effects. (Ferlito, 1993).
Microscopically, squamous epithelium (called matrix by the otologist) forms a cyst of
desquamating squames. The epithelium of a cholesteatoma and its cyst appears identical to that of
epithelial inclusion cysts. The epithelium may rest on granulation tissue or fibrous tissue.
(Topalogue et al., 1997).
Three separate types of cholesteatoma generally are identified on the basis of differing etiologies;
congenitally-acquired, primary-acquired, and secondary-acquired. Congenital cholesteatomas
arise as a consequence of squamous epithelium trapped within the temporal bone during
embryogenesis. Primary acquired cholesteatomas arise as the result of tympanic membrane
retraction. Secondary-acquired cholesteatomas occur as a direct consequence of some type of
injury to the tympanic membrane. This injury can be a perforation, which arises as a result of
acute otitis media or trauma, or may be due to surgical manipulation of the drum. (Topalogue et
al., 1997).
Bony erosion occurs by 2 principle mechanisms. Pressure effects produce bone remodeling, just as
what occurs regularly throughout the normal skeleton. Moreover, Enzymatic activity at the
margin of the cholesteatoma enhances osteoclastic activity, which greatly increases the speed of
bone erosion. These osteolytic enzymes appear to increase when a cholesteatoma becomes infected
(Topalogue et al., 1997).
Clinical picture
The hallmark symptom of cholesteatoma is painless otorrhea, either unremitting or frequently
recurrent. Hearing loss is common while dizziness is less common. Occasionally, cholesteatoma
will first present with the signs and symptoms of central nervous complications, like sigmoid sinus
thrombosis, epidural abscess, or meningitis. (Matra et al., 2003))
Investigations
CT scan is the imaging modality of choice. CT scan can detect subtle bony defects, and some
surgeons feel any patient with a cholesteatoma scheduled for surgical intervention should have a
preoperative CT scan. However, it cannot always distinguish between granulation tissue and
cholesteatoma. CT scan shows a non-specific, non-enhancing soft tissue mass that has a smooth
margin and variable bone erosion (Figure 28) (Lustig et al., 1998).