Cholesterol granulomas are rare, benign (noncancerous) cysts that can occur at the tip of the petrous apex, a part of the skull that is next to the middle ear.
The cysts are expanding masses that contain fluids, lipids, and cholesterol crystals, surrounded by a fibrous lining.
Granulomas can occur throughout the body as a reaction to foreign material. They usually have no symptoms or serious effects.
However, cholesterol granulomas of the petrous apex are dangerous because of their proximity to the ear and several important nerves.
If left untreated and the mass continues to expand, cholesterol granulomas of the petrous apex can cause:
Cholesterol granulomas can form when the air cells in the petrous apex are obstructed. The obstruction creates a vacuum that causes blood to be drawn into the air cells.
As red blood cells break down, cholesterol in the hemoglobin is released. The immune system reacts to the cholesterol as a foreign body, producing an inflammatory response.
Associated small blood vessels rupture as a result of the inflammation. Recurrent hemorrhaging makes the mass expand.
The surgical approach depends on the location of the cyst and the status of your hearing.
At UPMC, the preferred surgical treatment for cholesterol granulomas is the Endoscopic Endonasal Approach (EEA). This innovative, minimally invasive technique uses the nose and nasal cavities as natural corridors to access hard-to-reach or previously inoperable tumors and cysts. Benefits of EEA include:
To make the diagnosis of cholesterol granuloma, your doctor will examine your ear with an otoscope. The eardrum may appear blue, or a brownish protrusion behind it may be evident.
Symptoms may include:
Imaging tests such as MRI and CT scans aid in differentiating the cholesterol granuloma from other types of lesions. These studies also are useful for revealing its size and precise location.
Your doctor may also perform an audiogram to assess hearing loss.
Treatment involves drainage and ventilation of the cholesterol granuloma.
In cases where the granuloma is particularly large and destructive, surgical removal may be necessary. Access to the petrous apex is difficult and requires special surgical skills.
The treatment approach depends on the location of the mass, skills of the surgeon, and the status of your hearing.
Cholesterol granulomas of the petrous apex — particularly those with growth in the direction of the clivus, with midial expansion, or with inferior expansion under the level of the internal carotid artery — may be approached directly through the Endoscopic Endonasal Approach (EEA).This state-of-the-art, minimally invasive approach allows surgeons to access the tumor through the natural corridor of the nose, without making an open incision. Surgeons then remove the cholesterol granuloma through the nose and nasal cavities.
EEA surgery offers the benefits of no incisions to heal, no disfigurement, and a faster recovery time. In addition to being minimally invasive, EEA also preserves hearing.
Hearing may also be preserved using the infralabyrinthine or infracochlear approaches.
The translabyrinthine approach, in which an incision is made behind the ear, is rarely used. Generally, this approach is reserved for people who already have severe hearing loss, as it results in complete sensorineural loss of hearing.