Intralesional Methotrexate Injection for the Treatment of Epithelial Crateriform Tumor.

Background: Intralesional methotrexate injection (IL-MTX) is an appropriate strategy for treating epithelial crateriform tumors (ECTs) when surgical excision can result in functional or cosmetic defects; however, not all ECTs are responsive to this treatment.

Objective: This study aimed to evaluate the effectiveness of IL-MTX for ECTs and to determine the differences in clinical response according to the pathological features.

Methods: The medical records of patients treated with IL-MTX for their ECTs were retrospectively reviewed. Effectiveness was evaluated in terms of size reduction and flattening.

Results: Twenty-five cases of ECTs with biopsy were included in this study. Eight cases of keratoacanthoma (KA) and 15 cases of squamous cell carcinoma (SCC) were identified, but 2 cases could not be clearly distinguished. Seventeen patients (68%) showed a response after injection, and response rate in KA and SCC were 75% (6/8) and 60% (9/15), respectively. Nine patients showed complete resolution with IL-MTX. Patients received 3 injections, and regression was observed in 7.56 weeks after the first injection. According to histopathological results, patients with KA and SCC received 2 and 3.33 injections, respectively, and complete resolution was observed after 7 and 7.67 weeks, respectively.

Conclusion: IL-MTX is safe and effective, and could be considered as a useful non-surgical treatment option for ECTs. Both KA and crateriform SCC showed good response; However, KA showed a better response.