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Keratoacanthoma (KA) is a relatively common type of skin cancer. In general, KA is considered a low grade or well-differentiated type of squamous cell carcinoma; however, it tends to grow rapidly over a few weeks to months, locally invading surrounding tissues. A portion of KA can become invasive squamous cell carcinomas if they are not treated.
The cause of KA is not known. The majority of KA develop on sun exposed areas such as the face, neck and arms. Therefore, similar to other types of skin cancer, ultraviolet light and sun exposure is considered to be a major inciting factor. Other lesions have been reported to develop at sites of trauma to the skin. Trauma includes everything from a cut or scrap, a burn or previous surgical excision – even certain laser treatments have been associated with the development of these cancers.
On the skin, KA appear as dome-shaped bumps with a central crater which looks somewhat like a volcano. The crater can expand extremely rapidly in size over days to weeks. It is not uncommon for KA to double or even triple in size over very short periods of time.
KA’s are most effectively removed by surgical excision and Mohs surgery.The prognosis is excellent following surgery and the chance of recurrence is extremely low. Other treatments include electrodessication and curettage, and injections of methotrexate or a chemotherapeutic agent into the tumors. These latter approaches are often reserved from very large tumors or patients who are not good surgical candidates.
Normally there will be no problem with the KA or skin after treatment. Skin surgery is always associated with some risks – most common are bleeding, pain, scarring, necrosis and recurrence. It is very rare for a recurrence to form after removal, particularly after Mohs surgery. If a recurrence does occur, it usually forms on the edge of the previously treated skin cancer. In this case, the lesions can be readily treated again, with one of the methods described above.
Patients with KA’s are at risk of developing additional skin cancers and should use sunscreens when going out in the sun. A personal history of skin cancer increases a patient’s risk of developing additional skin cancers. Therefore, if you have a KA you should have your skin checked regularly by a dermatologist.
If you would like more information, or if you would like to schedule a consultation with one of our skin cancer specialists, please contact us today.
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