{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,29]],"date-time":"2026-09-29T13:21:26Z","timestamp":1790688086653,"version":"4.1.0"},"reference-count":39,"publisher":"Oxford University Press (OUP)","issue":"5","license":[{"start":{"date-parts":[[2025,7,11]],"date-time":"2025-07-11T00:00:00Z","timestamp":1752192000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"National Institute of Health and Social Care Research","award":["NIHR300774"],"award-info":[{"award-number":["NIHR300774"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2025,10,17]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:p>Mosaic disorders affecting pigmentation are a large group of different rare diseases that present with hypo- and\/or hyperpigmented birthmarks. These can have associated risks such as involvement of other organ systems, a predisposition to cancer and the possibility of transmission to future offspring as germline disease. However, clinical diagnosis of these conditions has been notoriously difficult, owing to the rarity of the conditions, the similarity of their cutaneous signs and the massive intradisease variability intrinsic to their pathogenetic mechanism. This review draws on the genetic and clinical discoveries of the last decade to introduce key concepts such as how to define a mosaic disorder, the relevance of small single pigmentary birthmarks, the occurrence of \u2018postnatal birthmarks\u2019 and the defining clinical features of mosaic disorders affecting pigmentation. It then lays out a modular classification for use in clinical practice and research studies, based on two independently variable features of the cutaneous signs: the developmental pattern and the lesion type. For the first time, the classification brings together macular lesions as well as naevi, epidermal as well as dermal lesions and hyper- and hypopigmented lesions, reflecting this unifying overview of aetiology. A companion smartphone iOS app for the clinical classification has been designed for use in clinic and is freely available online at \u2018What\u2019sThatSpot\u2019. The clinical importance of distinguishing mosaic disorders from germline disorders presenting with the same developmental patterns is discussed in the context of differential diagnoses. The third modular component of the classification (genotype) is addressed in the second part of this review.<\/jats:p>","DOI":"10.1093\/bjd\/ljaf262","type":"journal-article","created":{"date-parts":[[2025,7,11]],"date-time":"2025-07-11T16:48:37Z","timestamp":1752252517000},"page":"819-829","source":"Crossref","is-referenced-by-count":3,"title":["Mosaic disorders affecting pigmentation \u2013 part 1: how to make a clinical diagnosis"],"prefix":"10.1093","volume":"193","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-6256-327X","authenticated-orcid":false,"given":"Veronica A","family":"Kinsler","sequence":"first","affiliation":[{"name":"NHS England Rare Disease Collaborative Network for Mosaic Disorders, Paediatric Dermatology Department, Great Ormond Street Hospital for Children , London ,","place":["UK"]},{"name":"Genetics and Genomic Medicine programme, UCL Great Ormond Street Institute of Child Health , London ,","place":["UK"]},{"name":"Mosaicism and Precision Medicine Laboratory, the Francis Crick Institute , London ,","place":["UK"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"286","published-online":{"date-parts":[[2025,7,11]]},"reference":[{"key":"2026070712363633400_ljaf262-B1","doi-asserted-by":"crossref","first-page":"552","DOI":"10.1111\/bjd.17924","article-title":"Mosaic abnormalities of the skin: review and guidelines from the European Reference Network for rare skin diseases","volume":"182","author":"Kinsler","year":"2020","journal-title":"Br J Dermatol"},{"key":"2026070712363633400_ljaf262-B2","doi-asserted-by":"publisher","DOI":"10.1093\/bjd\/ljaf224","article-title":"Mosaic disorders affecting pigmentation \u2013 part 2: how to make a genetic diagnosis","author":"Kinsler","year":"2025","journal-title":"Br J Dermatol"},{"key":"2026070712363633400_ljaf262-B3","doi-asserted-by":"crossref","first-page":"218","DOI":"10.1542\/peds.58.2.218","article-title":"The incidence of birthmarks in the neonate","volume":"58","author":"Jacobs","year":"1976","journal-title":"Pediatrics"},{"key":"2026070712363633400_ljaf262-B4","doi-asserted-by":"crossref","first-page":"696","DOI":"10.1016\/S0022-3476(79)80713-1","article-title":"Birthmarks with serious medical significance: nevocullular nevi, sebaceous nevi, and multiple cafe au lait spots","volume":"95","author":"Alper","year":"1979","journal-title":"J Pediatr"},{"key":"2026070712363633400_ljaf262-B5","doi-asserted-by":"crossref","first-page":"58","DOI":"10.1111\/j.1525-1470.1983.tb01093.x","article-title":"The incidence and significance of birthmarks in a cohort of 4,641 newborns","volume":"1","author":"Alper","year":"1983","journal-title":"Pediatr Dermatol"},{"key":"2026070712363633400_ljaf262-B6","first-page":"220","article-title":"A birthmark survey in 500 newborns: clinical observation in two northern Taiwan medical center nurseries","volume":"30","author":"Shih","year":"2007","journal-title":"Chang Gung Med J"},{"key":"2026070712363633400_ljaf262-B7","first-page":"439","article-title":"Delineation of the various shapes and patterns of nevi","volume":"15","author":"Torrelo","year":"2005","journal-title":"Eur J Dermatol"},{"key":"2026070712363633400_ljaf262-B8","doi-asserted-by":"crossref","first-page":"1460","DOI":"10.1001\/archderm.1993.01680320094012","article-title":"Mosaicism in human skin. 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