Overview of Keratoacanthoma
Keratoacanthoma (KA) is a common skin tumor. In the past it was regarded as benign, but some of these tumors have been seen to transform into squamous cell carcinoma. Keratoacanthoma is now regarded and treated by many as a malignant growth. It is characterized by very rapid enlargement, followed by a stable period, and then a slow, natural regression.
Sun exposure appears to be the major factor contributing to KAs. Various chemical carcinogens (cancer-causing chemicals) have been shown to contribute to its incidence. KAs occur much more frequently in men than in women, usually in their 70s.
Signs and Symptoms of Keratoacanthoma
Most KAs occur on sun-exposed areas of the skin, with the greatest site of occurrence on the face and neck. Keratoacanthoma is also fairly commonly seen on the tops of heads. Its hallmarks are rapid growth, about an inch within weeks, followed by a stable stationary period. The lesion then slowly regresses over 2 to 6 months. A KA lesion is the color of the surrounding skin to pink. The central portion becomes a thick and scaly crater that sometimes breaks off, leaving an ulcer. If left to heal on its own, it regresses, leaving a small, pitted scar.
Keratoacanthomas are diagnosed based on their history and clinical presentation. As these lesions are usually removed, the pathologic picture is typical and confirms the diagnosis.
Treatment for Keratoacanthoma
Most KAs resolve spontaneously, but an underlying squamous cell carcinoma cannot be ruled out without removal of the tumor and microscopic evaluation. Living with the tumor while waiting for it to regress can be disturbing, not only because the lesion is often raised and unsightly, but also because it could become malignant.
Methods of eradication include surgical excision, which usually results in a very cosmetic appearing scar. Keratoancanthoma can also be treated with curettage and electrodesiccation, where the tumor is scraped out and the base is burned. Liquid nitrogen, an extremely cold chemical, can be applied to the lesion as well. Also, small doses of radiation and localized injections of chemotherapeutic agents can be effective.
Minimizing sun exposure can help prevent the occurrence of KAs.