Dermatoscopic features of labial melanotic macules in diverse skin types.

Background: Labial melanotic macules (LaMMs) are benign pigmented lesions that typically present as solitary patches on the lower lip. While their dermatoscopic features have been previously described, limited data exists on how these features vary across different skin types.

Objectives: To investigate the dermatoscopic differences of LaMMs in individuals with darker skin phototypes and compare them with lighter skin phototype LaMMs and mucosal melanomas.

Methods: This retrospective study analyzes 64 LaMMs located at the mucocutaneous junction or on the mucous membrane, collected from 49 patients and four mucosal melanomas across three tertiary dermatology centers in Turkiye, Austria, and Australia between January 1, 2020, and December 31, 2022. Two investigators reviewed clinical and dermatoscopic images independently, followed by a consensus evaluation to determine the presence of dermatoscopic criteria. Lesions that were clinically equivocal and not confirmed by histopathology were excluded.

Results: Multiple LaMMs were observed in 30.6% of the patients, and the majority of LaMMs (91.8%) were located on the lower lip. Overall, 53.1% of lesions exhibited asymmetry, 54.7% showed more than one dermatoscopic pattern, and 68.8% demonstrated multiple colors. No significant differences were noted between darker (n=30, 61.2%) and lighter (n=19, 38,8%) patients with LaMMs regarding age, sex, lesion location, or the presence of multiple lesions. LaMMs in darker skin were more likely to be asymmetrical and displayed multiple dermatoscopic patterns. White structureless areas and gray dots/clods were more frequently observed in darker skin type. All labial melanomas exhibited asymmetry, as well as multiple patterns and colors on dermatoscopic examination. There was no significant difference in the rates of asymmetry, multiple patterns, or multiple colors compared to LaMMs included in the study.

Conclusions: LaMMs in dark skin types more commonly present with asymmetry, multiple dermatoscopic patterns, and gray color.