Mosaicism happens when mutation occurs post-zygotically (i.e. post-conception) or when it affects the X chromosome in a female individual due to lyonization. Mutation affecting the keratinocytes also follows the lines of Blashko. On the other hand, mesodermal cells (i.e. fibroblasts) and neurons usually follow segmental or dermatomal pattern.

In this learning module, you will find a key point review on mosaicism and linear lesions focused on epidemiology, pathogenesis, clinical features, pathology, differential diagnosis and management.

1. Bolognia, J., Cerroni, L., & Schaffer, J. V. (2018). Dermatology. Philadelphia: Elsevier.

2. Wolverton, S. E. (2013). Comprehensive dermatologic drug therapy. Edinburgh: Saunders.