Dermoscopic features of labial melanotic macules in diverse skin types

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

To investigate the dermoscopic differences of LaMMs in individuals with darker skin phototypes and compare them with LaMMs and mucosal melanomas in individuals with lighter skin phototypes.

This retrospective study analysed 64 LaMMs located at the mucocutaneous junction or on the mucous membrane, collected from 49 patients and 4 mucosal melanomas across 3 tertiary dermatology centres in Australia, Austria and Türkiye between 1 January 2020 and 31 December 2022. Two investigators independently reviewed clinical and dermoscopic images, followed by a consensus evaluation to determine the presence of dermoscopic criteria. Lesions that were clinically equivocal and not confirmed by histopathology were excluded.

Multiple LaMMs were observed in 31% of the patients; most LaMMs (92%) were located on the lower lip. Overall, 53% of lesions exhibited asymmetry, 55% showed more than one dermoscopic pattern and 69% demonstrated multiple colours. No significant differences were noted between patients with darker (n = 30, 61%) or lighter (n = 19, 39%) skin phototypes with LaMMs regarding age, sex, lesion location or the presence of multiple lesions. LaMMs in patients with darker skin phototypes were more likely to be asymmetrical and display multiple dermoscopic patterns. White structureless areas and grey dots/clods were more frequently observed in patients with darker skin phototypes. All labial melanomas exhibited asymmetry, as well as multiple patterns and colours on dermoscopic examination. There were no significant differences in the proportions of asymmetry, multiple patterns or multiple colours compared with LaMMs.

LaMMs in patients with darker skin phototypes more commonly present with asymmetry, multiple dermoscopic patterns and grey colour.