JAMES M.GRICHNIKMD,phD ASHFAQ A.MARGHOOBMD ALONSCOPEMD
The parallel ridge pattern (PRP) is a volar dermoscopic pattern that is characterized by an accentuated pigmentation on the ridges of the skin markings, while the furrows are hypopigmented or unpigmented. It has been demonstrated to be highly specific for acral melanoma, and its presence must be considered a warning sign of melanoma. However, rare cases of benign acral melanocytic nevus can exhibit the PRP, as in the edge of the compound melanocytic nevus shown in Figure 1A. The acral blue nevus (Figure 1B) usually shows a bluish, quite homogeneous pigmentation involving the ridges.
Phan A, Dalle S, Marcilly M, Bergues J, Thomas L. Benign Dermoscopic Parallel Ridge Pattern Variants. Arch Dermatol. 2011;147(5):634. doi:10.1001/archdermatol.2011.47