Overview
- Keratoacanthoma (KA) is a rapidly growing, low-grade skin tumor that undergoes distinct evolutionary stages, typically characterized by rapid proliferation, stabilization, and eventual spontaneous regression. Due to similarities with squamous cell carcinoma (SCC), many experts now classify KA as “SCC-KA type,” advocating for excision to avoid misdiagnosis.
Surgical Treatment Options
- First-line treatment: Excisional procedure with 4 mm margins
- For lesions <2 cm on extremities: Electrodessication and curettage may be used
- For aggressive tumors >2 cm in cosmetically sensitive areas:
- Tissue-sparing approaches recommended
- Consider Mohs micrographic surgery
- For tumors with perineural invasion: Mohs micrographic surgery is the treatment of choice
Nonsurgical Interventions
- Limited evidence based primarily on case reports and retrospective reviews
- Options include:
- Topical 5% imiquimod cream
- Topical 5% 5-fluorouracil (5-FU) cream
- Intralesional methotrexate injections
- Intralesional bleomycin
- Intralesional 5-FU
- Oral isotretinoin
Intralesional Therapy Data
- Efficacy: 83-100% regression rates
- Most evidence supports: 5-FU and methotrexate
- Intralesional 5-FU administration:
- Dosage: 40-75 mg weekly
- Duration: 3-8 weeks
- Efficacy: Up to 98% response rate
Intralesional methotrexate:
- Limited evidence from smaller case series