Background: Anatomical and histopathologic correlates of the unique dermoscopic patterns seen in melanocytic nevi on acral volar skin is yet to be clarified.
Objective: Our aim was to investigate the relation between the dermoscopic patterns and anatomical and histopathological characteristics of melanocytic nevi on the sole.
Methods: The precise locations of 298 melanocytic nevi on the sole from 278 patients were retrospectively investigated, with attention paid to each dermoscopic pattern. In addition, 35 nevi showing each typical dermoscopic pattern were excised and evaluated histopathologically.
Results: Melanocytic nevi showing the parallel furrow pattern or the fibrillar pattern were located on the portions of the sole with regular parallel skin markings and were not found on the arch areas of the foot. Moreover, a subtle but distinctive difference in the distribution was observed between nevi of the two patterns; the nevi with the fibrillar pattern showed a tendency for the sites directly pressed by the body's weight. Melanocytic nevi of the lattice-like pattern were mostly located on the arch areas. Histopathologically, irrespective of the dermoscopic patterns, nests of nevus cells were mainly located in the epidermal rete ridges underlying the surface sulci. In the nevi with a fibrillar pattern, the cornified layer showed a slanting arrangement, which is considered to be a histopathological background of the fibrillar pattern.
Conclusion: Dermoscopic patterns seen in acral melanocytic nevi could be explained by the unique anatomical and histopathological characteristics of the acral skin.