Super-High Magnification Dermoscopy Can Help for the Diagnosis of Lentigo Maligna: a Pilot Study on 61 Cases

Abstract

Introduction: Facial lentigo maligna/lentigo maligna melanoma (LM/LMM) is a significant diagnostic clinical challenge and dermoscopy can help its diagnosis.

Objectives: The following study aimed to evaluate if super-high magnification dermoscopy at 400x can add further details for the diagnosis of the LM/LMM.

Methods: This is a retrospective observational, multicentric study enrolling patients who received a 20x and 400x (D400) magnification dermoscopic examination of facial skin lesions in clinical differential diagnosis with LM/LMM. Dermoscopic images were retrospectively evaluated by four observers for the presence/absence of nine 20x and ten 400x dermoscopic features. Univariate and multivariate analyses were carried out to find predictors of LM/LMM.

Results: We enrolled 61 patients with a single atypical skin lesion of the face, including 23 LMs and 3 LMMs. The presence of roundish and/or dendritic melanocytes (P < 0.001), irregular arrangement of melanocytes (P <0.001), irregular in shape and size melanocytes (P = 0.002), and folliculotropism of melanocytes (P <0.001) at D400 were more frequent in LM/LMM than other facial lesions. According to the multivariate analysis, roundish melanocytes at 400x dermoscopy were more indicative of LM/ LMM (Odds Ratio-OR 49.25, 95% CI 8.75-513.2, P < 0.001), and sharply demarcated borders at 20x dermoscopy were more indicative of not-LM/LMM (OR 0.1, 95% CI 0.01-0.79, P = 0.038).

Conclusions: D400 can identify atypical melanocyte proliferation and folliculotropism that can help to identify LM/LMM together with conventional dermoscopy data. Our preliminary observations should be confirmed by larger studies.

Figure 1

20x dermoscopy (A), clinical (B) and 400x dermoscopy (C–F) images of a lentigo maligna. 400x dermoscopy shows dendritic (red arrow) and roundish (yellow arrow) melanocytes and melanocytic invasion of a hair follicle (asterisk). Scale bar 100μm.

Figure 2

20x dermoscopy (A), clinical (B) and 400x dermoscopy (C–E) images of a solar lentigo. 400x dermoscopy shows pigmented keratinocytes (white arrow) in the epidermis around hair follicles (asterisk). Scale bar 100μm.