Stage-Specific Dermoscopic Patterns in Kaposi Sarcoma: A Retrospective Clinicodermoscopic Study

Introduction: Kaposi sarcoma (KS) is an angioproliferative neoplasm driven by HHV-8 infection that exhibits variable clinical morphology across stages. Dermoscopy offers a noninvasive tool to capture the evolving structural changes in these lesions. Objectives: This study aimed to characterize dermoscopic patterns of KS according to clinical stage and to correlate these findings with histopathological features. Methods: A retrospective analysis was conducted on 254 dermoscopically-documented KS lesions from 32 patients diagnosed between 2020 and 2024. Dermoscopic images were evaluated independently by two observers following the International Dermoscopy Society terminology. Statistical comparisons across patch, plaque, and nodular stages were performed using chi-square tests with Bonferroni correction. Results: Surface scale (75.2%) was the most common dermoscopic feature and increased significantly with advancing clinical stage (P=0.022). Polychromatic color change, collarette sign, ulceration, fiber sign, and blood spots were predominantly observed in plaque and nodular stages (P<0.001 for all). In contrast, pigment-related structures, particularly brown reticular lines and brown structureless areas (P<0.001), and four-dot clods (P=0.018) were significantly more frequent in patch lesions. Histopathologically, polychromatic color change corresponded to slit-like vascular spaces, erythrocyte extravasation, and hyaline globules, whereas pigment-related structures were associated with basal epidermal melanin and dermal hemosiderin deposition. Conclusions: Dermoscopic features of KS vary significantly with clinical stage and parallel histopathological progression. Recognition of these stage-specific patterns may enhance the non-invasive assessment of KS and aid clinical differentiation from other vascular and pigmented tumors.