Cholesterol granulomas are uncommon, benign cysts that can occur in the petrous apex, a part of the temporal bone of the skull that is next to the middle ear. They can be challenging to diagnosis as they resemble several other lesions. They are thought to be an inflammatory immune system response to cholesterol deposits left by the breakdown of blood vessels and cells. Cholesterol granulomas are made up of fluids, lipids, and cholesterol.
Pre-operative MRI showing a left petrous apex cholesterol granuloma
Causes of Cholesterol Granulomas
Within the skull there are numerous air-containing spaces called air cells. It was previously thought that blockage of those air cells caused cholesterol granuloma. A more recent theory, the "exposed marrow" hypothesis, suggests an inflammatory response to the by-products of eroded bone marrow cavities in the temporal bone.
Chronic middle ear infections may also cause cholesterol granulomas.
A few cases of cholesterol granuloma have been noted in families with familial hypercholesteremia.
Risks Associated with Cholesterol Granulomas
Chronic ear infections or head trauma can lead to cholesterol granuloma. If the mass continues to grow and is left untreated, it can eventually cause hearing loss, facial numbness, bone depletion and severe headaches.
Symptoms of Cholesterol Granulomas
Patients may be asymptomatic or symptoms may be vague and non-specific, delaying accurate diagnosis. Symptoms are related to the location and size of the tumor, and may include:
- Double vision
- Facial pain or spasm
- Change in facial sensation
- Hearing loss
Late symptoms include:
- Facial weakness
- Eustachian tube dysfunction, and middle ear effusion
- Cerebrospinal fluid leak
- Speech and swallowing problems
Pre-operative CT of the above lesion showing destructive changes extending medially to the skull base
Cholesterol granulomas are generally diagnosed after patients present with symptoms. Your doctor will take a medical history and order additional tests, such as:
- CT scan
The decision to treat or not to treat depends on the size of the lesion, how rapidly it is growing, and the severity of symptoms. Treatments range from active surveillance/monitoring to surgery, which may be performed minimally invasively. At Mount Sinai we offer endoscopic endonasal approach (removal through the nasal cavity and nose), removal through the ear via minimally invasive endoscopic surgery, or a combination of both. Typically one of the anatomical pathways is favorable over the other. Your surgeon at Mount Sinai will personalize your treatment for the best possible outcome.
Aside from treatment of middle ear infections, there is no known way to prevent cholesterol granuloma.
A fifty year old woman presented with intermittent facial numbness and pain over several months, which led to a MRI of the brain. A left medial petrous cholesterol granuloma was found, and she underwent extended transethmoidal microendoscopic surgery with Dr. Joshua B. Bederson and Dr. Eric M. Genden. She was discharged home on the third day. She did well and returned to work the following month. She continues to have annual MRIs with no sign of recurrence.
For more information or an appointment, call the Mount Sinai Department of ENT/Otolaryngology at 212-241-9410 or Neurosurgery at 212-241-2377.
Images used with permission from Joshua B. Bederson, MD