Psoriasis (psoriasis vulgaris, common psoriasis; Latin: psoria) is a chronic inflammatory skin disease characterized by the formation of characteristic plaques covered with white scales. The prevalence of this disease in the world is 2-3%. Psoriasis occurs more often in men than in women, and its incidence increases with age. The average age of onset of the disease is 30 years.
The etiology and pathogenesis of psoriasis are not fully understood. Most likely, the development of psoriasis is due to a combination of genetic and environmental factors. The role of genetic factors is confirmed by the fact that this disease often runs in families. In addition, it has been established that certain HLA antigens (e.g., DR4) are associated with an increased risk of developing psoriasis. Environmental factors include various infections (streptococcal throat infection), injuries to the skin, use of certain drugs (lithium salts, beta-blockers). There is also evidence that emotional stress can trigger or aggravate an attack of psoriasis.
The pathogenesis of psoriasis includes immunopathological mechanisms associated with changes in keratinocyte proliferation and differentiation as well as changes in immune reactions at the site of lesion formation. It is known that patients with this disease have an increased number of circulating lymphocytes and activated T cells in the affected areas which leads to an increased releaseof cytokines (TNF-alpha, IL-1 beta), resultingin local inflammationand further damage to keratinocytes . All these processes leadto thickeningof epidermisand formationof characteristic plaquescoveredwith whitesscaleson top(due tomassesof deadkeratinocytes). In additionto skin lesions , patientsmay alsodeveloparthritiswhich mostfrequentlyaffectsthe jointsperipheraljoints(dactylitis “sausagefinger”, “swanneckdeformity” ). Arthritispainfuland may significantlylimitpatient’smobilityand disrupt his/her daily activities . Lesscommonly otherorgans maybe involved:eyes(conjunctivitis , uveitis ), nails(nail dystrophy), intestines(“ulcerativecolitis -like”symptoms), etc..