The parallel pattern is found exclusively in melanocytic lesions on glabrous skin of palms and soles due to particular anatomic structures inherent to this location. Remarkably, the pigmentation may follow the sulci as well as the cristae of glabrous skin, but they may be rarely arranged also at a right angle to these pre-existing structures.

Diagnostic significance

The parallel pattern and certain modifications of this pattern have been described as a particular dermoscopic finding of acral melanocytic lesions by Saida et al. and Akasu et al. [Arch Dermatol 1995; Am J Dermatopathol 1996]. In detail, the parallel-furrow pattern, the lattice-like pattern, and the fibrillar pattern are commonly found in acral melanocytic nevi, whereas the parallel-ridge pattern is highly suggestive of melanomas on acral sites, as recently outlined by Oguchi et al. [Arch Dermatol 1998].