Abstract: | BACKGROUNDPityriasis alba affects 1% of the world population and about 9.9% of the children
in Brazil. However, its etiology remains uncertain.OBJECTIVEThe objective of the present study was to evaluate the immunoexpression of factor
XIIIa in dermal dendrocytes of skin lesions of pityriasis alba.METHODTwenty patients with pityriasis alba and 20 patients with atopic dermatitis
underwent biopsy. The dermal dendrocytes marked by factor XIIIa were counted by
means of immunohistochemical analysis.RESULTSThe mean amount of dermal dendrocytes found in the patients with pityriasis alba
was 2, whereas in the patients with atopic dermatitis it was 4, with a
statistically significant difference between them. A cutoff point of 3
cells/square inch was established to differentiate pityriasis alba from atopic
dermatitis, with 80% sensibility and 90% specificity.CONCLUSIONWe believe that pityriasis alba and atopic dermatitis should be considered
different clinical forms within the spectrum of atopic disease, in which sun
radiation plays an important role by modulating the progression of the
disease. |