The Puzzle of the Skin Patterns

Abstract

Background: The pattern of distribution of skin diseases remains one of the most elusive problems in dermatology, particularly when multiple pathologies are involved and coexistence of patterns is present. Most skin diseases show a predilection for certain body areas and are located in characteristic patterns. Many dermatoses exhibit lesions in a segmental fashion concomitantly with disseminated patterns. Sometimes the sites of predilection are inexplicable. Objectives: The main purpose of this paper is to give an overview on the peculiar arrangement of cutaneous lesions in both congenital and acquired skin disorders as well as reactive phenomena in vulnerable areas, in order to better recognise them clinically and understand their pathogenesis. Methods: Based on personal observations and a review of literature, this paper summarises the basics in understanding the patterned distribution of skin lesions, highlights the significance of the lines of Blaschko and their relationship with mosaicism, and describes some of the reactive skin phenomena. Results: Skin mosaicism plays a crucial role in the distribution and arrangement of skin lesions, as demonstrated by recent advances in genetic research in an increasing number of various skin diseases.

Facial involvement in annular pustular psoriasis: a rare clinical presentation

“…Most skin conditions show a predilection for certain body areas and are located in characteristic patterns. Intrinsic and/or extrinsic factors may explain the characteristic systematic pattern of many skin conditions 5 . However, exceptions do not contradict the established characteristic patterns of dermatoses.…”

Pigmentary anomaly caused by mosaic 3q22.2q29 duplication

“…The lines of Blaschko, first described by Alfred Blaschko in 1901, are known to represent the pathways of epidermal cell migration during embryonic development 4 . Various pigmentary abnormalities have been described along these lines.…”

“…Various pigmentary abnormalities have been described along these lines. These presentations are thought to be a result of different phenotypes within an individual resulting from epigenetic or genetic mosaicism 4,5 . In a high proportion of cases, blaschkoid dyspigmentation can be accompanied by extracutaneous manifestations, most commonly of the neurological type 6 …”

“…3 The lines of Blaschko, first described by Alfred Blaschko in 1901, are known to represent the pathways of epidermal cell migration during embryonic development. 4 Various pigmentary abnormalities have been described along these lines. These presentations are thought to be a result of different phenotypes within an individual resulting from epigenetic or genetic mosaicism.…”

“…These presentations are thought to be a result of different phenotypes within an individual resulting from epigenetic or genetic mosaicism. 4,5 In a high proportion of cases, blaschkoid dyspigmentation can be accompanied by extracutaneous manifestations, most commonly of the neurological type. 6 Our case is an example of genetic mosaicism resulting from a de novo genetic defect arising at some point in embryonic development.…”