Fibrillar pattern

Dermoscopic Description
Fine parallel lines of pigment, usually perpendicular to the dermatoglyphs. Seen on weightbearing areas of the soles, due to shearing forces on the thick skin. Holding the dermatoscope at an angle to look down along the furrow can help determine where the pigment originates.

What the structures correspond to histologically
Melanin in keratinocytes, usually in the furrows.

Lesions in which the structures arise
Benign acral naevi. Occasionally seen in melanoma especially if appear irregular (lines of different lengths and asymmetry).