Clinical and Histologic Features of Pityriasis Rosea and Pityriasis Lichenoides in Children

Kim, Hyoung Sup; Chang, Sung Nam; Kim, Dong Kun

Abstract

BACKGROUND: Pityriasis rosea is an acute inflammatory dermatosis with an unproven etiology. The typical clinical feature consists of an initial, single herald patch followed by development of smaller, disseminated, papulosquamous, ovoid macules. However, an unusual papular type of pityriasis rosea is relatively common in children and it shows similar clinical characteristics to pityriasis lichenoides.
OBJECTIVES
Our purpose was to observe the clinical and histologic features of pityriasis rosea and pityriasis lichenoides, and differentiate two diseases in children.
METHODS
Sixteen children with pityriasis rosea and nineteen children with pityriasis lichenoides were investigated clinically and histologically.
RESULTS
1. Clinically, pityriasis rosea may be differentiated from pityriasis lichenoides by the existence of herald patch, short duration, the uniformity of size and shape, and residual pigmentation. 2. Focal parakeratosis, intraepidermal vesicle and papillary derma edema are more common in pityriasis rosea. In contrast, deep dermal infiltration, dyskeratosis, epidermal necrosis and confluent parakeratosis are more common in pityriasis lichenoides. 3. Comparing to the plaque type, a papular type of pityriasis rosea shows more involvement in the extremities with longer duration. Histologically, parakeratosis and papillary dermal edema are less and spongiosis is more commonly observed in papular type.
CONCLUSIONS
Pityriasis rosea in children often shows papules especially on the extremities, similar to that of pityriasis lichenoides. However, from the results in this study, we believe that two diseases can be differentiated if both clinical and histologic findings are carefully studied.