Mucoscopy of lip squamous cell carcinoma and correlation with skin phototype and histological differentiation: a multicentric retrospective observational study by the International Dermoscopy Society

Background: There is a scarcity of published data on the dermoscopic morphology of lip squamous cell carcinoma (SCC) and its variability according to the histological differentiation degree and patient’s ethnicity as per skin phototype. Objectives: To evaluate the dermoscopic features of SCC of the lips and identify possible dermoscopic clues that may aid in differentiation between well-differentiated, moderately-differentiated, and poorly-differentiated lesions, as well as between “fair” skin (Fitzpatrick skin phototypes I-III) and “dark” skin (Fitzpatrick skin phototypes IV-VI). Methods: The clinical profile and dermoscopic images of patients of any age and either gender with histologically confirmed lip SCC collated from seven dermatological centers were retrospectively evaluated for dermoscopic clues as per certain predefined criteria. Results: A total of 60 lesions from 60 patients were included in the analysis. Histologically, well, moderate, and poordifferentiation were seen in 24 (40%), 14 (23.3%), and 22 (36.7%) of the lesions, respectively. Other than the presence of brown-to-gray dots/globules, which was exclusively seen in cases with dark phototypes (19.4% P = 0.035), no other dermoscopic feature was statistically significant in differentiating between the two skin types. Some dermoscopic findings were observed specifically with statistical significance: perivascular white halos (P = 0.049) and whitish-yellow background in well-differentiated lesions (P = 0.003); pink background in moderately-differentiated lesions (P = 0.003); and red background with dense vascularity in poorly-differentiated lesions (P < 0.001). Conclusions: The presence of vessels, scale/crust, and keratinization-associated white structures were the most common dermoscopic clues in lip SCC.