Clinical-Dermoscopic and Histopathologic Markers of Metastatic Risk in Early-Stage Thin Melanoma

Although considered early lesions, thin cutaneous melanomas still account for a notable portion of melanoma-related deaths, and their incidence continues to rise. We carried out a retrospective case-control analysis to determine which clinical-dermoscopic and histologic variables correlate with local or distant spread in melanomas measuring ≤0.8 mm. Records from 1 January 2000 through 22 June 2022 were reviewed from two specialized Italian dermatologic oncology centers. Sixteen individuals with metastasizing ≤0.8 mm melanomas were compared with controls who remained metastasis-free for at least 5 years. Statistical testing used Pearson’s chi-square or Fisher’s exact test. Out of 1396 eligible melanomas, 1.1% eventually metastasized. The median age at diagnosis was 49 years (range 28-83), with 56.3% male and 43.7% female. Tumors most often arose on the trunk (43.7%). Clinically, lesions were predominantly pigmented and frequently >10 mm (73.3%) with ≥3 hues (80%). Dermoscopy most commonly showed white areas (73.3%), atypical vascular structures (66.5%), blue-gray zones (60%), and an absent pigment network (60%). Histopathology revealed universally unfavorable traits, including regression (87.4%), mitoses within the dermis (50%), vertical growth (62.5%), and ulceration (12.5%). All of these differed significantly from controls (p < 0.05). For melanomas ≤0.8 mm, certain clinical and dermoscopic indicators, when combined with adverse tissue findings, may point toward a greater chance of metastatic behavior.