context: When cells clump together, they can form a cyst, a small sac that's filled with air, fluid, or something else. Sometimes, skin cells inside your ear can do this and cause a lump called a cholesteatoma. The lump typically starts deep in your ear near your eardrum and grows toward your middle and inner ear. Cholesteatomas aren't cancerous. But if you don't treat them, they can cause problems, including hearing loss. Cholesteatomas aren't common -- only 9 out of every 100,000 adults in the U. S. get them. They can show up at any age, and men are more likely to get them than women. Cholesteatomas typically cause symptoms in only one ear. The signs include: Constant sound inside your ear (tinnitus) Dizziness (or vertigo) Ear infection Earache Feeling of "fullness" in one ear Fluid that smells bad and leaks from your ears Trouble hearing in one ear Weakness in half your face If you've had a cholesteatoma for a long time and haven't treated it, it can grow into other areas of your ear, like the part you use for balance. More seriously, it can turn into an infection in your inner ear or even in your brain. This can cause pus-filled swelling in your brain or meningitis. Both are very rare. A cholesteatoma can happen for several reasons: You get an ear infection or injury. Sometimes after an operation on your ear, a cold, or an allergy, your Eustachian tube doesn't work normally. A vacuum is created in your middle ear, which sucks in your ear drum, making a sac -- the perfect place for skin cells to collect. Cholesteatomas caused by ear infections are the most common kind. You have a problem with a Eustachian tube. If the tube that connects your ear and your nose doesn't work the way it should, your eardrum can't handle changes in pressure well. That can make it collapse and become a pocket. Skin cells build up in the pocket and form a cholesteatoma. It forms when you do. In rare cases, cholesteatomas start when babies are still developing. Part of the lining of the ear gets trapped inside bone as it grows. These are usually found early in childhood. Your doctor will look inside your ear with an otoscope -- an instrument that has a magnifying glass and a light on it. She'll also test how well you can hear sounds to see if your cholesteatoma has affected your hearing. If your doctor thinks you might have a cholesteatoma, she'll refer you to an ear, nose, and throat specialist. There you'll get image scans such as the following so the doctor can look more closely at your cholesteatoma: CT scan (computerized tomography): This is a series of X-ray images that show your doctor a detailed picture of the bones, blood vessels, and soft tissue inside your ear. This can tell your doctor if your cholesteatoma has grown into the bones of your ear, which can mess with your hearing and balance. Your doctor may especially want to do this scan if surgery might be a treatment option for you. It can give him a better picture of what's going on before the procedure. MRI (magnetic resonance imaging): If a CT scan shows your doctor something that needs a closer look, an MRI is used if an infection is suspected to have spread to the brain. There's no medicine that will make a cholesteatoma go away. They usually need to be removed with surgery. It typically takes 2 to 3 hours, and you won't need to stay in a hospital. You'll be given medicine to make you sleep, and the removal will be done in one of two ways: Mastoidectomy: Your mastoid is the bone behind your ear. Your surgeon opens this bone up to remove the cyst. Tympanoplasty: This fixes damage to your eardrum (tympanic membrane). Your surgeon uses cartilage or muscle from another part of your ear to fill any holes in your eardrum. Surgery often helps with some of your hearing loss, but not always. Cholesteatomas can be aggressive. They can come back if they're not removed completely, so it's important to see your doctor for regular follow-up visits.