Arch Dermatol
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Comparative Study
A comparison of the dose-response relationship for psoralen-UVA erythema and UVB erythema.
Twenty patients with psoriasis were phototested to determine their erythemal responses to UVB and psoralen-UVA (PUVA) (oral 8-methoxypsoralen). The smallest ultraviolet radiation doses to produce erythema (minimal erythema dose and minimal phototoxic dose, respectively) were recorded and dose-response curves were constructed for UVB (24 hours after irradiation) and PUVA (48 hours) using objective measurement. The choice of a 48-hour measurement was validated by phototesting an additional 11 subjects to determine the time course of PUVA erythema. ⋯ The mean slope of the dose-response curve for UVB erythema was four times steeper than that for PUVA. Psoralen-UVA erythema reached a broad maximum between 48 and 96 hours after irradiation. Using objective methods we have demonstrated that the commonly accepted view of a steep dose-response relationship for PUVA erythema is not valid.
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Strongyloides stercoralis is a small intestinal nematode that has the ability to multiply within the human host. Because of the potential opportunistic behavior of this parasite, immunocompromised patients may develop fatal disseminated infections. ⋯ Rarely recognized is the presence of widespread petechiae and purpura that may develop in patients with disseminated infections. A 64-year-old immunosuppressed man developed fatal extraintestinal S stercoralis infection with extensive purpura associated with massive invasion of the skin by migrating larvae.
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Five case reports of perianal cellulitis caused by group A beta-hemolytic streptococci are presented. These reports illustrate delays in diagnosis and therapy of this condition that may present as chronic diaper dermatitis, perirectal fissures, painful defecation, fecal hoarding behavior, or proctocolitis. One patient had associated guttate psoriasis. In children especially, guttate psoriasis should alert physicians to culture perirectal as well as pharyngeal sites for group A streptococci.