Cutaneous Squamous Cell Carcinoma Arising From Hidradenitis Suppurativa and Epidermal Cyst: Clinical Characteristics, Baseline Neutrophil-To-Lymphocyte Ratio, and Disease-Specific Survival in a Retrospective Cohort.

Cutaneous squamous cell carcinoma (cSCC) may develop in chronic inflammatory settings, but clinicopathological features and outcomes remain poorly defined. To characterize clinical features and disease-specific survival (DSS) of cSCC arising from HS or EC in a single-institution cohort, and to assess baseline neutrophil-to-lymphocyte ratio (NLR) as a readily available inflammatory marker. We retrospectively reviewed 231 patients with cSCC diagnosed at a tertiary academic center between January 2013 and December 2024. After excluding 36 without baseline NLR data, a total of 195 patients were analyzed. Clinical characteristics, tumor staging, HS severity, baseline NLR, and DSS were evaluated. Of 195 evaluable patients, 8 had cSCC arising from hidradenitis suppurativa (HS), 5 from epidermal cysts (EC), 14 from burn scars, and 168 de novo (primary) cSCC. HS/EC-associated cSCC showed significantly higher baseline NLR than others (p = 0.016). In univariate analysis, primary tumor site, clinical T and N stages, baseline NLR, and HS/EC-associated lesion were significantly associated with DSS. Burn scar-associated cSCC was not significantly associated with DSS (p = 0.60). In multivariate analysis, clinical N and T stage (p < 0.05) and HS/EC-associated cSCC (p = 0.020; HR = 4.28, 95% CI, 1.26-14.6) remained independently associated with poorer DSS. In this cohort, cSCC arising from HS or EC was associated with elevated baseline NLR and poorer DSS. These findings suggest that HS/EC-associated cSCC may represent a clinically recognizable high-risk subgroup warranting careful surveillance, while the prognostic role of baseline NLR requires validation in larger studies.