Dermoscopic clues to lentigo maligna (LM) include asymmetrical pigmented follicular openings, perifollicular slate-gray dots and granules, circles within circles, atypical blood vessels, and linear pigmented lines forming rhomboidal structures.1 We have observed a previously unreported dermoscopic pattern in LM that consists of brown to bluish gray dots and lines arranged in an angulated linear pattern, creating a zig-zag appearance (Figures 1, 2, 3, and 4). The zig-zag pattern probably represents incompletely formed rhomboidal structures. Like other dermoscopic findings, the zig-zag pattern is not pathognomonic for LM, but in our experience, it is a suggestive dermoscopic pattern that may aid in the diagnosis of some otherwise difficult to diagnose LMs. All of the dermoscopic structures seen in LM can also be manifested in pigmented actinic keratoses, including the zig-zag pattern. However, one clinical clue to differentiate pigmented actinic keratoses from LMs is the presence of a rough texture in the former.
Slutsky JB, Marghoob AA. The Zig-Zag Pattern of Lentigo Maligna. Arch Dermatol. 2010;146(12):1444. doi:10.1001/archdermatol.2010.307