Melanomas on chronically sun-damaged skin (CSDS) can be difficult to identify and often manifest morphologic features that overlap with benign lesions.

We describe and analyze the clinical and dermoscopic characteristics of melanomas on nonfacial CSDS.

Melanoma cases on nonfacial CSDS were retrospectively identified from the biopsy specimen logs of 6 melanoma clinics. Clinical and dermoscopic images were combined into 1 database. Demographics, clinical, dermoscopic, and histopathologic information were analyzed. Descriptive frequencies were calculated.

One hundred eighty-six cases met the inclusion criteria: 142 melanomas in situ (76%) and 39 invasive (21%; mean thickness, 0.49 mm). Lentigo maligna was the most common histopathologic subtype (n = 76; 40.9%). The most frequent dermoscopic structures were granularity (n = 126; 67.7%) and angulated lines (n = 82; 44%). Vascular structures were more frequent in invasive melanomas (56% vs 12% of in situ melanomas). Most manifested 1 of 3 dermoscopic patterns: patchy peripheral pigmented islands, angulated lines, and tan structureless with granularity pattern.

This was a retrospective study, and evaluators were not blinded to the diagnosis. In addition, interobserver concordance and sensitivity and specificity for dermoscopic structures were not evaluated.

Outlier lesions manifesting dermoscopic structures, such as granularity, angulated lines, or vessels and any of the 3 described dermoscopic patterns should raise suspicion for melanoma.