Melanoma on sun damaged skin
Identifying melanomas located on chronically sun-damaged skin (CSDS) is challenging because their characteristics often clinically overlap with benign lesions. Dermoscopy has proven useful in detecting and differentiating melanoma from many benign lesions, including solar lentigo and seborrheic keratosis. The dermoscopic attributes associated with melanoma on sun-damaged skin of the face, primarily lentigo maligna are well described (see chapter). These descriptions may be dependent on the specific anatomic structure of the facial skin (ie, absence of rete ridge pattern and presence of pilosebaceous structures and hair follicles). The anatomy of sun damaged skin on other areas is different. This is characterized by atrophy of the epidemis and flattening of the dermoepidermal junction. This is the reason why melanoma on sun damaged skin looks different on non facial skin.
Jaimes et al. [1] recently described 3 different dermoscopy patterns for this entity:
Focal islands of pigmentation
The most frequent pattern is called "patchy peripheral pigmented islands’’, which consist of focal islands of pigmentation (network or structure-less areas) located towards the periphery of the lesion. Toward the center focal featureless areas, most often scar-like or hypopigmented, are observed. 13 (7%) of those melanomas had crystalline structures, and 21 (11.3%) revealed vascular blush, most commonly within the focal hypopigmented areas. This pattern was most frequently seen on the back (n = 43; 61.4%) and were rather large with an average size of 10.72 mm
Angulated line pattern
The second most common dermoscopic pattern is called ‘‘angulated line pattern’’; this was composed of angulated lines with or without the presence of granularity or circle within a circle and was most commonly seen on the upper extremities.
Tan structureless areas with granularity
The third pattern, consisted of lesions with tan structureless areas and granularity. These lesions had the smallest average diameter (7.39 mm) and occurred most frequently on the back.
Non-Specific pattern
21.5% of the lesions in this series did not have one of the 3 pattern describes previously but showed granularity, atypical network, peripheral tan structureless areas, atypical aggregated dots/globules, dotted vessels, milky red areas/vascular blush, serpentine vessels, asymmetric perifollicular hyperpigmentation, angulated lines, crystalline structures, and scar-like areas, negative network, off-centered blotch, and blue-white veil. Melanomas with a nonspecific pattern were more frequently seen on the back.
Here is an example of a melanoma on sun damaged skin with granularity and patchy peripheral pigmented islands:
