Cholesteatoma Workup

• CT scanning is the imaging modality of choice because CT scanning can detect subtle bony defects (see the image below). However, CT scanning cannot always distinguish between granulation tissue and a cholesteatoma. Even technically excellent fine-cut CT scans cannot reliably determine the full extent of disease. The surgeon cannot always predict what is needed in the operating room based on findings from the preoperative evaluation. Both the operating surgeon and the patient must understand this limitation of the preoperative assessment and be prepared for intraoperative surprises.^{[10, 11, 12]} Middle ear cholesteatoma. CT scan of an erosive cholesteatoma. The posterior canal wall has been eroded away, and the external auditory canal has filled with cholesteatomatous debris. Surprisingly, the middle ear is relatively free of disease.
• Gaurano (2004) has demonstrated that expansion of the mastoid antrum can be seen in 92% of middle ear cholesteatomas and, similarly, 92% had CT demonstrable erosion of the ossicles.
• The subtle bony defects that can be detected using CT a scan include the following:^[12]

  • Scutal erosion
  • Labyrinthine fistula
  • Defects in the tegmen
  • Details of ossicular involvement
  • Details of ossicular erosion or discontinuity
  • Anomalies or invasion of the fallopian canal
• MRI is used when very specific problems are expected to involve surrounding soft tissues. These problems including the following:^[12]

  • Dural involvement or invasion
  • Subdural or epidural abscess
  • Herniated brain into the mastoid cavity
  • Inflammation of the membranous labyrinth or facial nerve
  • Sigmoid sinus thrombosis
• A number of articles have recently appeared in the literature suggesting that diffusion weighted MRI may be able to distinguish between recurrent or persistent middle ear cholesteatoma and scar tissue or granulation tissue. If future studies verify both a high sensitivity and specificity, replacing routine second look procedures with high quality diffusion weighted MRI images may be possible.^{[13, 14]}
• Some surgeons reserve preoperative imaging for only special cases and are quite comfortable performing surgery without it. These surgeons may request a preoperative CT scan in the following circumstances:

  • If the diagnosis is in doubt: The diagnosis may be in doubt in individuals with only small attic retractions observed during the physical examination. CT scanning may help distinguish between shallow retractions without soft tissue extension into the epitympanic space and an extensive soft tissue mass with bony erosion. CT scanning can be helpful in individuals who have already had tympanomastoid surgery. In this group of patients, a white mass behind the tympanic membrane, as shown below, could represent tympanosclerosis, cartilage, or a recurrent cholesteatoma. CT scan findings frequently help resolve such questions. Diffusion weighted MRI may also be helpful in such circumstances. Middle ear cholesteatoma. A congenital cholesteatoma. A white mass can be seen behind an intact drum.
  • If the patient is adamant about avoiding an operation: Poor surgical candidates or patients who wish to avoid an operation for other reasons can be better advised about the risks of nonsurgical management if a CT has been performed and findings are evaluated. The presence of extensive disease, labyrinthine fistula, encroachment on the fallopian canal, and involvement of the oval window niche increase the risk of expectant management.
  • Helping a patient or parents assess some of the risks of ossicular involvement is often useful: If ossicular involvement is apparent on preoperative CT scans, parents should be counseled that ossicular removal may be necessary and significant postoperative conductive hearing loss should be expected.
  • If the underlying anatomy is indeterminate and the extent of disease is unclear as the result of previous surgery
  • In patients with congenital anomalies (eg, atresia cases, individuals with craniofacial anomalies)
  • If complications are suspected.
  • If labyrinthine fistula or erosion of the fallopian canal is suspected: In this case, CT scanning remains the procedure of choice.
  • If intracranial invasion, dural inflammation, meningitis, abscess, or sigmoid sinus thrombosis is suspected, MRI is indicated.
• Other surgeons believe any patient with a cholesteatoma who is scheduled for surgical intervention should have a preoperative CT scan. They believe that useful information is obtained in every circumstance and, consequently, that the expense and radiation exposure is always justified.

Incisional biopsies are unnecessary because the diagnosis can be made based on physical examination and radiography findings.

Audiometry should be performed prior to surgery whenever possible. Occasionally, a serious complication may require urgent surgery, and, in such cases, audiometric testing can be foregone. Air conduction, bone conduction, speech reception threshold, and speech discrimination scores should all be determined within a few weeks of the proposed operative procedure. No other diagnostic tests are generally necessary.

The histology findings from surgically removed cholesteatoma specimens demonstrate typical squamous epithelium. The histology is indistinguishable from that of sebaceous cysts or keratomas removed from any other portion of the body.