It is a chronic inflammatory skin disorder clinically characterized by erythematous, sharply demarcated papules and rounded plaques, covered by silvery micaceous scale.
About half of all patients with psoriasis have fingernail involvement, appearing as punctate pitting, nail thickening, or subungual hyperkeratosis. About 5 to 10% of patients with psoriasis have associated joint complaints, and these are most often found in patients with fingernail involvement.
Evidence has accumulated clearly indicating a role for T cells in the pathophysiology of psoriasis. Stimulation of immune function with cytokines such as IL-2 has been associated with abrupt worsening of preexisting psoriasis, and bone marrow transplantation has resulted in clearance of disease.
Diagnosis of psoriasis
The differential diagnosis should include pityriasis rosea and secondary syphilis. Patients with psoriasis may also develop pustular lesions. These may be localized to the palms and soles or may be generalized and associated with fever, malaise, diarrhea, and arthralgias.
Patients with psoriasis may also develop pustular lesions. These may be localized to the palms and soles or may be generalized and associated with fever, malaise, diarrhea, and arthralgias. Agents that inhibit activated T cell function are often effective for the treatment of severe psoriasis. Presumably, cytokines from activated T cells elaborate growth factors that stimulate keratinocyte hyperproliferation.
Treatment of psoriasis
All patients should be instructed to avoid excess drying or irritation of their skin and to maintain adequate cutaneous hydration. A topical vitamin D analogue (calcipitriol) is also efficacious in the treatment of psoriasis. The evidence implicating psoriasis as a T cell-mediated disorder has created a new perspective relating to the treatment of psoriasis.
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