Background and objectives: Keratoacanthoma (KA) is a variant of a well-differentiated squamous cell carcinoma (SCC). The tumour is characterized by spontaneous regression. Clinical and histological differentiation from an invasive SCC may be very difficult. Therefore, treatment of a KA suspected lesion is necessary. Surgical excision is the treatment of choice for solitary KA’s. In some cases, this may be difficult because of localization and/or size of the tumour and when cosmetically unacceptable results are expected. Intralesional methotrexate (MTX) may be a potential treatment option for KA’s.

Methods: 21 patients with a KA suspected lesion based on clinical and histopathological aspects were treated with intralesional MTX between 2006 and 2011.

Results: Intralesional MTX achieved complete remission in 86%, requiring an average of 2.3 injections with an average of 16 days apart. Three patients had a slight reduction in tumour size where biopsy finally showed a SCC. In these cases, treatment consisted of surgery (2) and radiotherapy (1).

Conclusion: Intralesional treatment with MTX can be an effective and simple treatment in these cases. Adequate follow-up is necessary.

Key words : keratoacanthoma, methotrexate, treatment