Kelly’s family doctor found a growth in her ear canal, and now Kelly is in the ear specialist’s office to see what’s going on. It turned out to be pretty simple: a slow-developing benign bone growth caused by a lot of exposure to cold water. We’ll check it again in two years to make sure it is not starting to block the canal.
Most bony lesions of the ear canal are caused by swimming in cold water. They are almost always benign growths. They are frequently referred to as osteomas, but they are more accurately called exostoses. In most cases, neither causes symptoms but they may be discovered during a routine ear examination.
Problems occur if these growths enlarge enough to block the ear canal. This may lead to cerumen impaction and recurrent outer ear infections (if the growth traps cerumen and water). In rare cases, bony lesions may grow into the eardrum leading to conductive hearing loss. Exostoses and osteomas are separate clinical entities that differ in their cause as well as appearance.
Exostoses
Exostoses (the plural form of exostosis) are growths of new bone in the bony portion of the ear canal. They are caused by repeated exposure to cold water, which stimulates the lining of bone to produce new bone layers (see figure 15.1). Surfers, who often find the best waves in colder water, are commonly affected by this condition. In addition to the cold water, surfers are also exposed to winds that cause evaporation of water from the ear canal. Evaporation further cools the ear, stimulating bone growth. Exostosis is often called surfers’ ear in areas where the sport is popular.
Figure 15.1. Bony growths of the ear canal are almost always benign but may enlarge over time to obstruct the canal. A small proportion require surgical removal.
One recent study found that exostoses were larger in ears that faced prevailing winds. Up to 73.5 percent of surfers have exostoses. Multiple growths, affecting both ears to different degrees, are frequently found in adults with a history of cold water surfing.
Exostoses have tiny layers of new, reactive bone that is formed on top of the normal bone of the ear canal. When studied under a microscope, these layers can look like the consecutive rings seen on growing trees. The lesions are broad-based and lack a central core.
Osteoma
Osteomas, unlike exostoses, are single, involve only one side, and have a stem-like base. Osteomas are more common in children and young adults. Most of the time osteomas are discovered during routine ear examination. They tend to be whitish, smooth, round masses covered with healthy skin and partially obstructing a view of the eardrum.
Osteomas differ from exostoses in that the normal layers of bone are organized around a central core that contains blood vessels. They attach to the underlying bone by a narrow stem and in some ways resemble a tiny mushroom.
Diagnosis and Treatment
A history and clinical exam are usually sufficient for diagnosing bony lesions of the ear canal. In circumstances in which the diagnosis is in doubt, or to assess the extent of the disease when the ear canal is completely obstructed, CT scans can be useful.
Most bony masses require no treatment and have no associated risk. They should be observed every two to three years to see if further growth begins to block the ear canal. Blockage could lead to recurrent wax impactions or infection and may signal the need for surgical removal of the tumor.
Surgical removal of exostoses is done under a microscope. Skin of the ear canal is removed from the surface of the growth and replaced after the growth is surgically removed. Care is taken to avoid damage to the eardrum in order to preserve hearing. The abnormal bone is removed with a drill and the patient is left with a skin-covered, healthy ear canal.
In smaller exostoses, it is possible to operate through the natural ear opening. This avoids an incision. This approach may not be possible when the growth is large or the canal is small. When more access is necessary, an incision is made behind the ear or in the cartilage of the ear canal. Either incision provides excellent access. These operations have a high rate of success and few complications. However, continued cold-water surfing may result in recurrence of growths.
Surgery for osteomas is usually simple because they rise on a narrow stem. Osteomas can be removed under local or general anesthesia as an outpatient procedure. Recurrence is uncommon.