The patterns of birthmarks suggest a novel population of melanocyte precursors arising around the time of gastrulation.

Veronica A Kinsler,Lionel Larue

doi:10.1111/pcmr.12645

Abstract

SummarySystematic work in the mouse and chicken has mapped out two neural crest‐derived pathways of melanocyte precursor migration. With these in mind, this study reappraises the patterns of congenital pigmentary disorders in humans and identifies three recurrent patterns consistent across genetically different diseases. Only two of these are seen in diseases known to be melanocyte cell‐autonomous. The segmental pattern correlates well with the classical dorsolateral population from animal studies, demonstrating respect of the midline, cranio‐caudal axial mixing, unilateral migration and involvement of key epidermally derived structures. Importantly however, the melanocyte precursors responsible for the non‐segmental pattern, which demonstrates circular, bilateral migration centred on the midline, and not involving key epidermally derived structures, have not been identified previously. We propose that this population originates around the time of gastrulation, most likely within the mesoderm, and ultimately resides within the dermis. Whether it contributes to mature melanocytes in non‐disease states is not known; however, parallels with the patterns of acquired vitiligo would suggest that it does. The third pattern, hypo‐ or hyperpigmented fine and whorled Blaschko's lines, is proposed to be non‐cell‐autonomous.

Highlights

Extensive and systematic work in the mouse and chicken over the last 50 years has studied the pathways of melanocytic precursor migration (Bonaventure, Domingues, & Larue, 2013; Mort, Jackson, & Patton, 2015)
Summary Systematic work in the mouse and chicken has mapped out two neural crest-derived pathways of melanocyte precursor migration
This study reappraises the patterns of congenital pigmentary disorders in humans and identifies three recurrent patterns consistent across genetically different diseases

Summary

Introduction

Extensive and systematic work in the mouse and chicken over the last 50 years has studied the pathways of melanocytic precursor migration (Bonaventure, Domingues, & Larue, 2013; Mort, Jackson, & Patton, 2015). Two major pathways of migration have been identified and characterized, both originating from the neural crest. The first is the classical dorsolateral pathway in both mouse and chick, in which melanoblasts delaminate from the neural crest and migrate between the developing somites and overlying dermis (Erickson & Goins, 1995). The second is the more recently described dorsoventral pathway in the chick, in which melanoblasts develop from Schwann cell precursors in association with peripheral nerves (Adameyko et al, 2009). There is fate specification before migration, whereas in the dorsoventral pathway, the melanocytes develop after the initial migration of a multipotent Schwann cell precursor. Recent ex vivo imaging and mathematical modelling of the murine dorsolateral melanoblast population has concluded that melanoblast migration is by processes of random diffusion and proliferation coupled with

Methods

Discussion

Conclusion