What is the treatment for Keratoacanthoma (squamous cell carcinoma-like skin cancer)?

Treatment of Keratoacanthoma (Squamous Cell Carcinoma-like Skin Cancer)

Surgical excision is the recommended first-line treatment for keratoacanthoma, as it provides both definitive treatment and allows for complete histological assessment to rule out invasive squamous cell carcinoma. 1

Understanding Keratoacanthoma

Keratoacanthoma is considered a variant of squamous cell carcinoma (SCC) with distinct clinical features:

• Presents as a rapidly growing, dome-shaped lesion with a central keratinous plug 2
• Typically appears on sun-exposed areas, with approximately 80% occurring on the face 2
• May spontaneously regress over 6-12 months, but evidence for universal regression is lacking 2, 3
• Histologically can be difficult to distinguish from well-differentiated SCC 4, 3

Treatment Algorithm

First-Line Treatment Options

1. Surgical Excision (Preferred)

   • Standard excision with 4-6 mm margins for low-risk lesions 1
   • Mohs micrographic surgery (MMS) recommended for high-risk lesions 1
   • Provides complete histological assessment to rule out invasive SCC 2
   • Local flap or full-thickness graft closure offers superior cosmetic results 2

2. Alternative Treatments for Low-Risk Lesions

   • Curettage and electrodesiccation (C&E) may be considered for low-risk lesions in non-hair-bearing locations 1
   • Radiation therapy can be considered when surgical therapy is not feasible 1
   • Cryosurgery may be considered when more effective therapies are contraindicated 1

Treatment Selection Based on Risk Factors

Low-Risk Features:

• Small size (<2 cm diameter) 1
• Superficial depth (<4 mm) 1
• Well-differentiated histology 1
• Location on sun-exposed sites (excluding lip and ear) 1

High-Risk Features:

• Larger size (>2 cm diameter) 1
• Greater depth (>4 mm or Clark level V) 1
• Poor differentiation 1
• Perineural or vascular invasion 1
• Immunosuppressed patient 1
• Location on lip, ear, scalp, eyelids, or nose 1

Special Considerations

Immunosuppressed Patients

• Require more aggressive treatment and closer follow-up 1
• May benefit from reduction in immunosuppressive therapy in cases of multiple or aggressive tumors 1
• Consider multidisciplinary management 1

Alternative Therapies for Special Situations

• Intralesional methotrexate has shown efficacy in resolving keratoacanthoma-type SCC in select cases 5
• Photodynamic therapy may be used as an adjunct to surgery in challenging cases 6
• Topical 5-fluorouracil and imiquimod are not recommended for primary treatment of SCC based on available data 1

Follow-up Recommendations

• After diagnosis, screening for new skin cancers should be performed at least annually 1
• Patients should be counseled on skin self-examination and sun protection 1
• Follow-up frequency should be tailored to the risk of recurrence or development of new lesions 1

Important Caveats

• Despite the potential for spontaneous regression, waiting for regression is not recommended due to risk of misdiagnosis or malignant transformation 2, 3
• Incomplete biopsies may lead to inconclusive or erroneous diagnoses 2
• The distinction between keratoacanthoma and SCC can be challenging even for expert pathologists 4, 3
• Some experts consider keratoacanthoma to be a clinically distinct variant of well-differentiated SCC capable of spontaneous regression 3

By following this treatment algorithm and considering the individual risk factors, keratoacanthoma can be effectively managed to minimize morbidity and mortality while preserving function and cosmetic outcomes.