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Pityriasis alba: a study of pathogenic factors
Author(s) -
Blessmann Weber M,
Sponchiado de Ávila LG,
Albaneze R,
Magalhães de Oliveira OL,
Sudhaus BD,
Ferreira Cestari T
Publication year - 2002
Publication title -
journal of the european academy of dermatology and venereology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.655
H-Index - 107
eISSN - 1468-3083
pISSN - 0926-9959
DOI - 10.1046/j.1468-3083.2002.00494.x
Subject(s) - medicine , phototype , atopy , dermatology , etiology , atopic dermatitis , hygiene , allergy , population , malassezia , immunology , pathology , environmental health
Abstract Background The aetiology of pityriasis alba (PA), a common dermatosis in childhood, is still controversial. The objective of this study was to assess the possible aetiopathogenic factors of this disease in infants. Methods Forty‐four patients with PA and 31 healthy children were examined and compared. Personal hygiene habits, sun exposure, presence of Staphylococcus aureus in nasal fossae and presence of major or minor signs of atopy were assessed during anamnesis and physical examination. Susceptibility to ultraviolet (UV) B radiation was measured by the onset of a contact hypersensitivity reaction to diphenylcyclopropenone in individuals sensitized in previously irradiated areas. Results The prevalence of PA was higher in individuals with darker skin, in high phototype categories, as well as in males. The number of daily baths and sun exposure between 10.00 h and 15.00 h were significantly higher in the PA group when compared with controls ( P = 0.03 and P = 0.0015, respectively). The presence of atopy signs was more common in pityriasis patients ( P = 0.002). Susceptibility to UVB radiation was 29.6% in the PA group vs. 29.0% in the control group; nevertheless, important differences were found after stratification in order to control possible confounding factors. The presence of S. aureus in the nostrils was equal in both groups. Conclusions Our results confirm that PA, in our population, is more prevalent in males and in individuals in higher phototype categories. In those with inadequate personal hygiene and sun exposure habits the disease is more accentuated, demonstrating that the xerosis presenting in individuals with atopic diathesis is an important element in the development of the disease. S. aureus is not an important aetiopathogenic factor in PA. Susceptibility to UVB becomes important when related to the patient's phototype.