Medical Care
Treatment of keratoacanthoma (KA) is primarily surgical. Reserve medical treatment for exceptional cases where surgical intervention is either not feasible or desirable. For example, medical intervention may be appropriate in patients with multiple lesions, in lesions not amenable to surgery because of size or location, and in patients with comorbidities that dissuade surgical procedure.
Systemic retinoids, such as isotretinoin, are a consideration for patients with lesions too numerous for surgical intervention.
Intralesional methotrexate (MTX), [29] 5-fluorouracil, bleomycin, and steroids have been used with success in patients who are either poor surgical candidates or have lesions not amenable to surgery because of size or location. [26, 30] A 2007 review of the use of intralesional injection of MTX on 38 patients, including 18 of the researchers' patients, showed a 92% clinical "resolution" rate; however, patients needed an average of 2.1 injections to achieve it. Only 13% (5 patients) obtained histological confirmation. [31] Forty lesions in 30 patients were cleared with intralesional 5-fluorouracil with an average of three injections. [32] Topical 20% fluorouracil was also effective in 14 patients, but two developed allergic contact dermatitis. [33] Topical imiquimod has been used with anecdotal success. [34]
Note much of the literature concerning medical intervention for keratoacanthoma is limited to case reports or case series. Be cautious when making the decision to pursue medical in lieu of surgical intervention and perform appropriate follow-up.
Surgical Care
The primary therapy for keratoacanthoma is surgical excision of the tumor. Excise tumors with adequate margins (3-5 mm) and histopathologic evaluation to exclude invasive SCC. Partial shave biopsy usually inadequately distinguishes between keratoacanthoma and invasive SCC. In some patients, smaller lesions may be treated with deep excisional shave and curettage or other destructive techniques. Because the biological behavior of an individual keratoacanthoma cannot be predicted, many consider surgical treatment of keratoacanthoma to be equivalent to treatment for SCC.
Mohs micrographic surgery may be indicated for large or recurrent keratoacanthomas or keratoacanthomas located in anatomic areas with cosmetic or functional considerations.
Keratoacanthomas are radiosensitive and respond well to low doses of radiation (< 10 Gy). Radiation therapy may be useful in selected patients with large tumors in whom resection will result in cosmetic deformity or for tumors that have recurred following attempted excisional surgery. Radiation therapy is less appealing in younger patients in whom radiation damage worsens with time. Radiation therapy is an important alternative treatment for selected patients who understand the risks and benefits, who are not good surgical candidates, or who lack access to Mohs surgery.
Both laser therapy and cryotherapy have been used successfully in small keratoacanthomas, in keratoacanthomas found in difficult to treat locations, and as an adjunct to surgical removal.
Consultations
Consult a dermatologist to exclude invasive squamous cell carcinoma (SCC).
Long-Term Monitoring
Patients who develop nonmelanoma skin cancer, such as keratoacanthoma, squamous cell carcinoma (SCC), Bowen disease, or basal cell carcinoma, are at high risk for developing subsequent nonmelanoma skin cancer. Education, periodic follow-up examinations, and early detection and treatment of actinic keratosis and skin cancer are important in these patients.
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Keratoacanthoma (squamous cell carcinoma-keratoacanthoma or SCC-KA type) on inner canthus.
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Keratoacanthoma of the left forehead.
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Close-up view of the keratoacanthoma.
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Keratoacanthoma lesion (squamous cell carcinoma-keratoacanthoma or SCC-KA type).
