Dermoscopic clues to differentiate facial lentigo maligna from pigmented actinic keratosis

anciBackground Dermoscopy is limited in differentiating accurately between pigmented lentigo maligna (LM) and pigmented actinic keratosis (PAK). This might be related to the fact that most studies have focused on pigmented criteria only, without considering additional recognizable features. Objectives To irisestigate the diagnostic accuracy of established dermoscopic criteria for pigmented LM and PAK, but including in the evaluation features previously associated with nonpigmented facial actinic keratosis. Methods Retrospectively enrolled cases of histopathologically diagnosed LM, PAK and solar lentigo/early seborrhoeic keratosis (SL/SK) were dermoscopically twain ated for the presence of predefined criteria. Univariate anci multivariate regression analyses were performed arid receiver operating characteristic curves were used. Results The study sample consisted of 70 LMs, 56 PAKs and 18 SL/SKs. In a multivariate analysis, the most potent predictors of LM Were grey rhomboids (sixfold increased probability of LM), nonevident follicles (fourfold) and intense pigmentation,ofold). In contrast, white circles, scales and red colour were significantly correlated with PAK, posing a 14-fold, eightfold and fourfold probability for PAK, respectively. The absence of evident follicles also represented a frequent LM criterion, characterizing 710 of LMs. Conclusions White and evident follicles, scales and red colour epresent significant diagnostic clues for PAK. Conversely, intense pigmentation arid grey rhomboidal lines appear highly suggestive of LM.