Intralesional Methotrexate for the Treatment of Keratoacanthoma: a Prospective Study

Introduction:
Keratoacanthomas are rapidly growing cutaneous neoplasms known for their potential to spontaneously regress over time. Treatment can be challenging due to the potentially large field size and number of lesions. Intralesional methotrexate has proven to be an effective non-surgical treatment for keratoacanthomas, as demonstrated by our experience.

Objectives:
To study the efficacy of intralesional methotrexate injections for the treatment of keratoacanthoma. Secondary objectives: To evaluate the efficacy of intralesional methotrexate injections for keratoacanthoma based on the patient age and sex, as well as lesion duration and size.

Material and methods:
We treated 37 patients with keratoacanthomas using intralesional methotrexate. Injections were administered weekly, followed by 10 mg of folic acid taken 24 hours later. We used 15 mg of methotrexate for keratoacanthomas smaller than 20 mm, and 20 mg of methotrexate for keratoacanthomas larger than 20 mm. Methotrexate was injected at the base of the keratoacanthomas tumors using a 27-gauge needle at each treatment session. Shortly after the methotrexate injection, uniform tumor blanching was achieved. The injection site, the interval between injections, and the concentration and amount of methotrexate were adjusted based on the clinical response.

Results:
Most patients experienced complete resolution of the lesions after 4 to 8 injections.

Conclusions:
Intralesional methotrexate is an effective and safe nonoperative treatment modality for keratoacanthoma, particularly in anatomically sensitive locations, areas difficult to treat with surgery, elderly debilitated patients, and those who refuse surgery.