Schematic drawing of the anatomy of glabrous skin.  

Note that the crista intermedia corresponds to the crista superficialis where the acrosyringium reaches the surface. The crista limitans correlates with the sulcus superficialis and nests of melanocytes situated around the crista limitans dermoscopically reveal a pigmentation following the sulcus superficialis, also called parallel-furrow pattern. This is the most common dermoscopic pattern in acral melanocytic nevi. 
Additional patterns frequently found in benign nevi of this particular anatomic site are the lattice-like pattern, formed by a pigmentation following and crossing the furrows, and the fibrillar pattern, exhibiting numerous, fine pigmented filaments perpendicular to the furrows. In contrast to the parallel-furrow pattern, the parallel-ridge pattern is characterized by a pigmentation aligned along the cristae superficiales. The knowledge of the latter pattern is important because it is commonly found in melanoma in situ and early invasive melanomas of palms and soles.

 



Typical parallel pattern, also called parallel-furrow pattern, in an acral nevus



Variation on the theme of parallel-furrow pattern in an acral nevus



Variation on the theme of parallel pattern, also called lattice-like pattern,  in an acral nevus



Variation on the theme of parallel pattern, also called fibrillar pattern, in an acral nevus



Parallel-ridge pattern in an acral melanoma in situ