Intralesional methotrexate for keratoacanthoma: a case series from a Portuguese dermatology department

Objective: The aim was to report the experience of a Portuguese dermatology department using intralesional methotrexate (MTX) for keratoacanthoma (KA). Methods: A retrospective descriptive study was conducted, including five patients with histologically confirmed KA treated with weekly intralesional MTX (MTX-IL), which was injected into the periphery and center of the lesion without local anesthesia. Treatment was repeated until complete necrosis or marked regression. Clinical outcomes, adverse events, and follow-up data were analyzed. Results: Four men and one woman (mean age 68.8 years) were treated. Lesions (5-20 mm) were located on cosmetically or functionally sensitive sites. All achieved complete resolution after one to seven injections. The largest lesion showed transient inflammatory enlargement with necrosis before progressive regression. No adverse events or recurrences were observed during 4-12 months of follow-up. Conclusion: MTX-IL appears to be a safe, effective, and cosmetically favorable non-surgical option for KA.