A comparative clinicopathological study of pityriasis lichenoides chronica and small plaque parapsoriasis

Kim, Duck Ha; Park, No Jae

Abstract

A clinicopathological study of 12 cases of pityriasis lichenoides chronica and 14 cases of small plaque parapsoriasis was performed. Patients with pityriasis lichenoides chranica ranged in age from 15 to 62 years (mean, 30 years) with male predominance. They had erythematous or reddish scaly papules occuring mostly on both trunk and extremities(92%). The lesions were about the size of r ice grains or small peas. Patients with small plaque parapsoriasis ranged in age from 8 to 67 years(mean, 33 years) and presented yellowish or erythematous scaly maculies and patches comrnonly involving the trunk and extremities(64%). The size of the lesions were larger than those of pityriasis lichenoides chronica. Histopatbologically, the distinct feature of pityriasis lichenoides chronica was vacuolar alteration at the dermoepidermal junction characterizing interface dermatitis. The microscopic findings of small plaque parapsoriasis were, although not as distinct as in pityriasis lichenoides chronica, those af either spongiotic dermatitis or superfirial peri vascula dermatitis. We conclude from this study that these two conditions have different clinical and histologic features and we propose that the term guttate parapsoriasis shauld not be used as a synonym of either pityriasis lichenoides rhronica or small plaque parapsoriasis.