Dermoscopy of Lentigo Maligna Melanoma

Report of 125 Cases

P. Pralong; E. Bathelier; S. Dalle; N. Poulalhon; S. Debarbieux; L. Thomas

Disclosures

The British Journal of Dermatology. 2012;167(2):280-287. 

In This Article

Materials and Methods

Setting

One hundred and twenty-five cases of histopathology-proven LMM from the melanoma register of a single institution (Service de Dermatologie, Université Claude Bernard Lyon 1, Centre Hospitalier Lyon Sud, France) were analysed. This was an unselected consecutive retrospective series recruited from 2001 to 2009. Ethical committee approval was waived.

Patients

For each patient, information on sex and age at the time of diagnosis was retrieved from medical records. Clinical description of the primary lesion was based on medical records and clinical preoperative photographs (Canon EOS 350D camera with Canon 60 mm EFS macro lens and Canon MT-24EX macro twin lite flash; Canon, Tokyo, Japan): the precise anatomical site and maximum diameter of the lesion were calculated on the basis of standardized digital images. The Breslow thickness and Clark level were retrieved from histopathological records.

Dermoscopy

All lesions were photographed in vivo with a camera connected to an immersion dermoscope. We adopted a colourless jellified antiseptic solution (Purell®; Gojo, Lille, France) for immersion. Before 2005, photographs were taken with a standard dermoscopic camera (Dermaphot®; Heine, Herrsching, Germany), and later ones with a polarized light immersion dermoscopic camera (DermLite FOTO®; 3Gen, San Juan Capistrano, CA, U.S.A.).

All lesions were independently analysed by three different examiners (P.P., E.B. and L.T.). The studied criteria are listed in Table 1.

In addition to classical dermoscopic features of LMM and of extrafacial nonacral melanoma we studied four previously undescribed features: darkening at dermoscopic examination, target-like pattern, red rhomboidal structures and increased density of the vascular network. We defined as 'darkening at dermoscopic examination' the observation on dermoscopic images of the presence of a colour, invisible to the naked eye, and darker than all clinically observable shades of brown or grey (Fig. 2). We defined as 'target-like pattern' the presence of a dark dot in the centre of the dark circle of a hyperpigmented hair follicle. This dark dot was not a hair. We defined as 'red rhomboidal structure' a lozenge-shaped vascular pattern occurring in the area separating the hair follicles from the others. 'Increased density of the vascular network' was defined as a vascular network of higher density within the lesion than in peripheral skin (Figs 3–6). All the other recorded features have been widely and thoroughly described in the classical dermoscopic literature.[7,13–20] We examined five geometric subtypes of pigmented follicular openings: semicircle, fine circle, signet ring-like circle, irregular circle and double circle (Fig. 7). Granular-annular pattern and peppering (granulation) were, in some cases, difficult to distinguish, particularly when the annular-granular pattern was slate-grey. Better to recognize and classify these two entities, we focused on global distribution of slate-grey granules: when granules were found somewhat aggregated we subclassified them as peppering, and when granules were found regularly around the follicles we referred to them as an annular-granular pattern (Fig. 8).

Figure 2.

Lentigo maligna melanoma. Clinical appearance (1) and darkening at dermoscopic examination (2).

Figure 3.

Target-like pattern (white arrows). Lentigo maligna melanoma on the cheek, Breslow thickness 0·2 mm, Clark level III.

Figure 4.

Red rhomboidal structures (dark arrows). Lentigo maligna melanoma on the temple, Breslow thickness 0·25 mm, Clark level II.

Figure 5.

Increase of vascular density in lesion. Lentigo maligna melanoma on the cheek, Breslow thickness 0·15 mm, Clark level II.

Figure 6.

Original new features: increase of vascular density in lesion (left), red rhomboidal structures (middle) and target-like pattern (right).

Figure 7.

The different pigmented follicular openings studied in our study.

Figure 8.

Differences of granule distribution between annular-granular pattern (a) and peppering (b).

Data Analysis

For clinical and histopathological features, results were described in numbers. Dermoscopic criteria were coded dichotomously (yes: present, no: absent). To compare the baseline characteristics of subgroups we used Pearson's χ2 test.

Comments

3090D553-9492-4563-8681-AD288FA52ACE
Comments on Medscape are moderated and should be professional in tone and on topic. You must declare any conflicts of interest related to your comments and responses. Please see our Commenting Guide for further information. We reserve the right to remove posts at our sole discretion.
Post as:

processing....