Parapsoriasis and related disorders

Abstract

Key Features: Erythema, scaling, and a variable degree of atrophy are the major characteristics of parap-soriasis; crops of spontaneously regressing erythematous papules characterize pityriasis lichenoides. Small plaque parapsoriasis has a benign course. Pityriasis lichenoides et varioliformis acute (PLEVA) is characterized by crusted vesicular or pustular lesions and pityriasis lichenoides chronica (PLC) by scaly lesions. Large plaque parapsoriasis may develop into cutaneous lymphoma. Pityriasis lichtenoides sometimes develops into a lymphomatoid papulosis. CD42 T cells dominate in large plaque psoriasis, and T cell clonality is observed in this condition. In pityriasis lichenoides, T cell clonality can be observed and CD42 cells prevail in PLC, but CD82 cells in PLEVA Treatment options comprise: topical corticos-teroids, topical tacrolimus, topical coal tar, photo(chemo)therapy, topical and systemic retinoids, and anti-TNF-α treatments. © 2010 Springer-Verlag Berlin Heidelberg.