Abstract

At our institution, we define keratoacanthoma-like atypical squamous proliferations (KASPs) as well-differentiated squamous proliferations in which atypical cells comprise less than half of stroma-adjacent keratinocytes. Digital spatial profiling as well as p53 labeling have been used to distinguish these low-grade lesions from squamous cell carcinoma (SCC) in many cases. These lesions commonly arise on the lower legs of elderly patients with extensive sun damage, for whom surgical excision, the standard of care for cutaneous squamous cell carcinoma, can cause significant morbidity with respect to wound healing and loss of functionality, as well as inciting additional lesions. Based on prior reports of similar lesions arising in surgical scars responding to intralesional triamcinolone injection, we hypothesized that intralesional injection of 40 mg/mL triamcinolone would prove sufficient to treat KASPs of the lower legs. During the 2023-2024 academic year, 13 lesions underwent this conservative therapy, with patient ages ranging from 80 to 91 years (average 89.2 years). At three month follow up, all lesions had resolved clinically, and repeat shave biopsy of one of the lesions confirmed complete histologic resolution. In summary, distinction between low-grade KASPs and true SCCs by dermatopathologists may help to prevent unnecessary morbidity by guiding clinicians toward conservative, non-surgical management of these low-grade lesions on the lower legs of elderly patients.