Chapter 053. Eczema and Dermatitis (Part 6)

Psoriasis (Table 53-2) Psoriasis is one of the most common dermatologic diseases, affecting up to 1% of the worlds population. It is a chronic inflammatory skin disorder clinically characterized by erythematous, sharply demarcated papules and rounded plaques, covered by silvery micaceous scale. The skin lesions of psoriasis are variably pruritic. Traumatized areas often develop lesions of psoriasis (Koebner or isomorphic phenomenon). Additionally, other external factors may exacerbate psoriasis including infections, stress, and medications (lithium, beta blockers, and antimalarials).Table 53-2 Papulosquamous DisordersClinical FeaturesOther Notable FeaturesHistologic FeaturesPsoriasisSharply demarcated,May be aggravatedAcanthosis,by vascularerythematous plaques certain with mica-like scale; infection; predominantly elbows, severe knees,...
Nội dung trích xuất từ tài liệu:
Chapter 053. Eczema and Dermatitis (Part 6) Chapter 053. Eczema and Dermatitis (Part 6) Psoriasis (Table 53-2) Psoriasis is one of the most common dermatologic diseases,affecting up to 1% of the worlds population. It is a chronic inflammatory skindisorder clinically characterized by erythematous, sharply demarcated papules androunded plaques, covered by silvery micaceous scale. The skin lesions of psoriasisare variably pruritic. Traumatized areas often develop lesions of psoriasis(Koebner or isomorphic phenomenon). Additionally, other external factors mayexacerbate psoriasis including infections, stress, and medications (lithium, betablockers, and antimalarials).Table 53-2 Papulosquamous Disorders Clinical Other Histologic Features Notable Features FeaturesPsoriasis Sharply May be Acanthosis, demarcated, aggravated by vascular erythematous plaques certain drugs, proliferation with mica-like scale; infection; predominantly elbows, severe forms knees, and scalp; seen associated atypical forms may with HIV localize to intertriginous areas; eruptive forms may be associated with infectionLichen planus Purple Certain Interface polygonal papules drugs may dermatitis marked by severe induce: pruritus; lacy white thiazides, markings, especially antimalarial associated with drugs mucous membrane lesionsPityriasis rosea Rash often Variable Pathologic preceded by herald pruritus; self- features often patch; oval to round limited nonspecific plaques with trailing resolving in 2– scale; most often 8 weeks; may affects the trunk, and be imitated by eruption lines up in secondary skin folds giving a fir syphilis tree-like appearance; generally spares palms and soles Dermatophytosis Polymorphous KOH Hyphae appearance depending preparation and neutrophils in on dermatophyte, may show stratum corneum body site, and host branching response; sharply hyphae; culture defined to ill- helpful demarcated scaly plaques with or without inflammation; may be associated with hair loss The most common variety of psoriasis is called plaque-type. Patients withplaque-type psoriasis will have stable, slowly enlarging plaques, which remainbasically unchanged for long periods of time. The most commonly involved areasare the elbows, knees, gluteal cleft, and the scalp. Involvement tends to besymmetric. Plaque psoriasis generally develops slowly and runs an indolentcourse. It rarely remits spontaneously. Inverse psoriasis affects the intertriginousregions including the axilla, groin, submammary region, and navel; it also tends toaffect the scalp, palms, and soles. The individual lesions are sharply demarcatedplaques (see Fig. 52-7), but they may be moist and without scale due to theirlocation.