Tissue immunostaining for factor XIIIa in dermal dendrocytes of pityriasis alba skin lesions

BACKGROUND

Pityriasis alba affects 1% of the world population and about 9.9% of the childrenin Brazil. However, its etiology remains uncertain.

OBJECTIVE

The objective of the present study was to evaluate the immunoexpression of factorXIIIa in dermal dendrocytes of skin lesions of pityriasis alba.

METHOD

Twenty patients with pityriasis alba and 20 patients with atopic dermatitisunderwent biopsy. The dermal dendrocytes marked by factor XIIIa were counted bymeans of immunohistochemical analysis.

RESULTS

The mean amount of dermal dendrocytes found in the patients with pityriasis albawas 2, whereas in the patients with atopic dermatitis it was 4, with astatistically significant difference between them. A cutoff point of 3cells/square inch was established to differentiate pityriasis alba from atopicdermatitis, with 80% sensibility and 90% specificity.

CONCLUSION

We believe that pityriasis alba and atopic dermatitis should be considereddifferent clinical forms within the spectrum of atopic disease, in which sunradiation plays an important role by modulating the progression of thedisease.