Causes and risk factors
The cause of psoriasis is unknown, but is often a positive family history, suggesting a genetic component in many cases (family antecedents of psoriasis are identified in a third of cases).
Psoriasis mechanism corresponds to accelerated renewals of the epidermis cell (the top layer of skin) every 4 days, though normal cycle is 28 days. Given because life of the cells is the same, they form and accumulate thick crusts.
- streptococcal infection ( Beta-hemolytic )
- Local irritation (Koebner phenomenon)
- stopping treatment with some medications (cortisone)
- some medications (chloroquine, beta blockers, indomethacin, lithium, interferon alpha)
- Ingestion of toxic substances (alcohol, tobacco, etc.)
- Sleep disorders
- Genetic predisposition - over a third of patients, one or more family members also suffer from psoriasis. If a parent shows this condition, the risk to the child varies between 5 and 10%.
- Immunological reactions against another disease (chickenpox)
- Reaction to a medication (lithium, beta-blockers) or vaccine
- A systemic infection (pharyngitis or streptococcal angina)
- Skin lesions
- Dry climate
- Prolonged exposure to sunlight or certain chemical substances ( paint thinners or disinfectants)
- Excessive alcohol consumption.