Dermoscopic characteristics of congenital melanocytic nevi affecting acral volar skin

To characterize the dermoscopic features of acral congenital melanocytic nevi (CMN).

Retrospective independent evaluation of dermoscopic images by 2 dermoscopists.

A dermatology clinic at a university hospital.

Using the files of the clinic from January 1, 2004, through February 28, 2009, we selected cases with CMN lesions affecting acral volar skin that were present at birth or developed within the first few months of life.

Characteristic dermoscopic features and their frequencies.

We collected a total of 24 acral CMN lesions. Dermoscopically, 9 lesions (38%) showed a combination of the crista dotted pattern and the parallel furrow pattern. Of these 9 lesions, 1 also had a fibrillar pattern. The remaining 15 lesions showed the following single-component patterns: the parallel furrow pattern in 6 (25%), the crista dotted pattern in 3 (12%), the fibrillar pattern in 2 (8%), and the globular, globulostreaklike, nontypical, and parallel ridge patterns in 1 each (4%). We also followed up 6 lesions for several years. Changes in the dermoscopic features were observed in 4 CMN lesions from patients younger than 14 years. Three lesions had a combination of the crista dotted and parallel furrow patterns on the first visit that changed to the nontypical pattern; in addition, the degrees of pigmentation decreased during follow-up. In the remaining lesion, the globulostreaklike pattern changed to the parallel furrow pattern.

Most CMN lesions affecting acral volar skin show characteristic dermoscopic features distinguishable from acral melanoma. The combination of the crista dotted and parallel furrow patterns (ie, peas-in-a-pod pattern) is the most common feature in acral CMN. Some lesions of acral CMN fade during childhood.