Three-dimensional melanin distribution of acral melanocytic nevi is reflected in dermoscopy features: analysis of the parallel pattern.
BACKGROUND
Acral melanocytic nevi have parallel patterns on dermoscopy; however, it is not understood why pigment distributions exhibit such patterns.


OBJECTIVE
To clarify the reason why melanin distributions in acral melanocytic nevi exhibit a parallel pattern on dermoscopy.


METHODS
A serial sectioning perpendicular to the skin markings was performed, and each section was stained with modified Fontana-Masson staining to pick out melanin granules. These sections were then reconstructed to three-dimensional images by an image processing software, and these three-dimensional images were analyzed.


RESULTS
Melanin columns in the cornified layer were mainly seen in the dermoscopic images of acral melanocytic nevi. In the parallel-furrow pattern melanin columns were arranged vertically, and in the fibrillar pattern they were arranged in a slanting fashion.


CONCLUSIONS
Melanin columns in the cornified layer, not melanin in the basal layer, mainly contribute to the dermoscopic pattern of acral melanocytic nevi.
Kimoto
M
M
Department of Dermatology, Keio University School of Medicine, Tokyo, Japan. kimotoma@1998.jukuin.keio.ac.jp
Sakamoto
M
M
Iyatomi
H
H
Tanaka
M
M
D046169:Dermoscopy; D005534:Foot Diseases / Q000473:pathology*; D006225:Hand / Q000473:pathology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008543:Melanins / Q000032:analysis* / Q000378:metabolism; D009508:Nevus, Pigmented / Q000473:pathology*; D012835:Silver Nitrate; D012867:Skin / Q000378:metabolism / Q000473:pathology; D012878:Skin Neoplasms / Q000473:pathology*
C051037:Fontana-Masson stain; D008543:Melanins; D012835:Silver Nitrate