Treatment of keratoacanthoma: Is intralesional methotrexate an option?

BACKGROUND Keratoacanthomas (KAs) are a variant of squamous cell carcinomas. Some KAs have shown aggressive behaviour, leading to metastasis and death. Surgical excision is the treatment of choice for most KA patients. Intralesional methotrexate (MTX) may also be a potential treatment option for KAs. OBJECTIVE To evaluate intralesional MTX as a treatment modality for KA. METHODS A retrospective chart review of nine patients with KAs treated with intralesional MTX was performed. Each patient had biopsy-proven KA. The lesion was initially debulked, and MTX was injected at the base. Patients were seen weekly in the office, and reinjected with intralesional MTX depending on the response of the lesion. Each patient was evaluated for their response to the intralesional MTX injections, the number of injections required and complications. RESULTS Patients required approximately two to four intralesional injections (12.5 mg to 25 mg per injection) before KA resolution. Eight of nine (88.9%) patients experienced complete resolution of their tumours. One patient experienced treatment failure, and underwent surgical excision of the KA. The average follow-up period was 2.8 years, and there were no recurrences. CONCLUSION The results from the present retrospective study show that intralesional MTX injection is an effective treatment option for KAs. The authors propose that intralesional MTX injection with initial debulking of the KA should be used as a first line of treatment when KAs present on the extremities, in cosmetically sensitive areas and in elderly patients with multiple comorbities.