INTRODUCTION
Keratoacathoma (KA) is a unique clinical pathological entity that is difficult to categorize. Differentiating a KA from a squamous cell carcinoma (SCC) is important for treatment implications but is often challenging. Clinically, aggressive SCC may present similarly to KA with rapid growth over weeks. Furthermore, it is often challenging, histologically, to distinguish between KA and SCC without an excisional biopsy.1-3 While some KAs have shown the ability to spontaneously involute,4 others have progressed to high-risk SCC or metastasized.5,6 A malignant course in suspected KA is thought to be more likely the result of diagnostic confusion with SCC rather than malignant transformation.3 We report a patient with a solitary KA of the skin of the right ala successfully treated with intralesional (IL) injections of methotrexate (MTX). We also provide a review of the literature on IL-MTX as a treatment modality for KA.
REPORT OF A CASE
A 53-year-old woman presented with an eight week history of a rapidly enlarging 1cm in diameter nodule on the right nasal ala (Figure 1). Incisional biopsy revealed a squamous cell carcinoma, keratoacanthoma type, with lesional tissue extending to the base of the biopsy. The lesion was injected with 1cc of methotrexate (25 mg methotrexate/mL) three times, with an interval of one week between injections. After each treatment, involution of the lesion was observed (Figure 2, 3). Four weeks after the first treatment, the lesion had completely resolved. No recurrence of the lesion was noted during a follow-up at 6 months (Figure 4).
DISCUSSION
There is a great deal still unknown of the etiology and patho
