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Background: Pigmentary mosaicism (PM), also known as Blaschkoid dyspigmentation, is a rare pigmentary anomaly. Although several case reports have been published describing extracutaneous manifestations associated with PM, there are very few studies on the clinical characteristics of patients with PM., Aim: To describe the clinical characteristics of patients with PM., Patients and Methods: This descriptive cross-sectional study was conducted among 47 children examined by a dermatologist and a pediatrician. The pattern and location of the PM, type of pigmentation and extracutaneous manifestations were documented., Results: The most common pattern of PM was narrow-band PM, followed by broad-band and checkerboard patterns. The trunk was the most affected region, followed by the legs and arms. PM manifested as hypopigmentation in 51.1% of cases, as hyperpigmentation in 27.6%, and as hypo/hyperpigmentation in 21.2%. Accompanying diseases were present in 40.4% of patients: neuropsychiatric diseases were the most common, followed by endocrinological or hematological diseases and growth/developmental delay., Conclusion: PM has been associated with several extracutaneous findings but there is still some debate whether these associations reflect different PM phenotypes or whether they are simply coincidental. Our study suggests that extracutaneous involvement in PM patients is frequent, thus warranting careful examination of PM patients., (Copyright © 2023 Elsevier Masson SAS. All rights reserved.)

The occurrence of abnormally pigmented skin lesions is a common phenomenon and often associated with the influence of ultraviolet radiation (UV) and other sources of DNA damage. Pigmentary lesions induced by UV radiation and other sources of DNA damage occur in healthy individuals, but human diseases with defective DNA repair represent important models which allow the investigation of possible underlying molecular mechanisms leading to hypo-and hyperpigmentations. There are several hereditary diseases which are known to go along with genetic defects of DNA repair mechanisms comprising Xeroderma pigmentosum (XP), Cockayne syndrome (CS), Trichothiodystrophy (TTD), Werner syndrome (WS), Bloom syndrome (BS), Fanconi anemia (FA) and Ataxia telangiectasia (AT). These diseases share clinical characteristics including poikilodermatic skin changes such as hypo-and hyperpigmentation. Since UV radiation is the most common source of DNA damage which can cause pigmentary lesions both in healthy individuals and in patients with genetic deficiency in DNA repair, in the present article, we focus on pigmentary lesions in patients with XP as an example of a disease associated with genetic defects in DNA repair., (Copyright © 2012 Elsevier Masson SAS. All rights reserved.)

Pigmentary changes in Asians are larger problems and more important features of aging than wrinkles. Melasma is a commonly observed epidermal hypermelanosis of the face in Asians. The altered dermal structures and impaired basement membrane are thought to have an influence on the development of epidermal hyperpigmentation of melasma. Dermal hyperpigmentary diseases are particularly common in Asians. Acquired bilateral melanosis of the neck is a characteristic dermal melanotic condition primarily of the neck in peri-menopausal women. It is characterized by marked accumulation of dermal pigment with perivascular lymphocytic infiltration. The cases seem to represent a continuum of Riehl's melanosis. Subclinical injury or inflammation may play a role as possible causative factors for the development of the pigmentation., (Copyright © 2012 Elsevier Masson SAS. All rights reserved.)