Differentiating keratoacanthoma (KA) from cutaneous squamous cell carcinoma (cSCC) remains challenging, particularly in crateriform keratinocytic tumors with clinicopathological overlap and diagnostic variability. Although histopathology is essential for diagnosis, its ability to reliably predict biological behaviour and therapeutic response in this setting is limited. We conducted a retrospective single-centre study of 33 patients (mean age 78 years, range 50-97) with keratinocytic tumors treated with intralesional methotrexate (ilMTX) between 2018 and 2023, to assess whether clinical morphology predicts treatment outcome more reliably than histological classification. Complete resolution was achieved in 20/33 cases after a mean of 4.5 injections. Crateriform symmetric tumors showed significantly higher response rates than non-crateriform tumors (85% vs 23.1%; p < 0.001). Tumor size and histological subtype were not significantly associated with outcome. Adverse events were mild and reversible. Clinical crateriform morphology may represent a practical predictor of response to ilMTX and help guide therapeutic decision-making in cases with equivocal histopathology.
Sanz et al. (Fri,) studied this question.