Phacomatosis Pigmentokeratotica Is Caused by a Postzygotic HRAS Mutation in a Multipotent Progenitor Cell  Leopold Groesser, Eva Herschberger, Ana Sagrera, Tor Shwayder, Katharina Flux, Laura Ehmann, Andreas Wollenberg, Antonio Torrelo, Lorea Bagazgoitia, Blanca Diaz-Ley, Sigrid Tinschert, Ilske Oschlies, Sebastian Singer, Marion Mickler, Agusti Toll, Michael Landthaler, Francisco X. Real, Christian Hafner  Journal of Investigative Dermatology  Volume 133, Issue 8, Pages 1998-2003 (August 2013) DOI: 10.1038/jid.2013.24 Copyright © 2013 The Society for Investigative Dermatology, Inc Terms and Conditions

Figure 1 Clinical manifestations of phacomatosis pigmentokeratotica (patient 4). (a) Overview of a sebaceous nevus involving the right side of the scalp, neck, and back in close vicinity to a speckled lentiginous nevus on the left side of the back. It is noteworthy that a trichoblastoma (arrowhead) had developed on the sebaceous nevus of the scalp. (b) Detail of the sebaceous nevus (right) and the speckled lentiginous nevus (left). (c) A hairy congenital melanocytic nevus adjacent to the speckled lentiginous nevus was noted on the back. Journal of Investigative Dermatology 2013 133, 1998-2003DOI: (10.1038/jid.2013.24) Copyright © 2013 The Society for Investigative Dermatology, Inc Terms and Conditions

Figure 2 Histological findings and corresponding RAS SNaPshot multiplex assay chromatograms (patient 4). (a) The sebaceous nevus shows abundant sebaceous glands and the HRAS c.37G>C mutation (blue peak; peaks indicate the DNA antisense strand of the HRAS gene). (b) The speckled lentiginous nevus showed the histopathology of a melanocytic compound nevus. The HRAS c.37G>C mutation was present in the melanocytic nevus cells in the dermis (left), whereas keratinocytes revealed a wild-type sequence at codon 13 of HRAS (right). (c) The congenital melanocytic nevus showed a deep infiltrate of melanocytic nevus cells in the dermis that revealed the HRAS c.37G>C mutation. Journal of Investigative Dermatology 2013 133, 1998-2003DOI: (10.1038/jid.2013.24) Copyright © 2013 The Society for Investigative Dermatology, Inc Terms and Conditions