In psoriasis – colloquially called psoriasis – (synonyms: Acrodermatitis continua pustulosa; Acrodermatitis continua suppurativa; Acrodermatitis perstans; ICD-10 L40.-: Psoriasis) is a systemic disease that includes skin symptoms (irregularly circumscribed inflammatory and scaly papules/nodules; predominantly on the knees, elbows, and scalp), possible joint involvement, and characteristic comorbidities.
Psoriasis is a common disease.
The following forms of psoriasis can be distinguished:
- Psoriasis vulgaris type I – positive family history and clear association with HLA-Cw6; accounts for 60-70% of all psoriasis cases.
- Psoriasis vulgaris type II – often negative family history and less pronounced association to genetic markers; 30-40% of cases.
Other forms of psoriasis occurrence are:
- Psoriasis arthropathica (arthritis psoriatrica; psoriatic arthritis, PsA) – occurrence of the described skin changes with simultaneous arthritis (joint inflammation) of the small joints such as the finger or toe joints; accounts for 20% of cases.
- Psoriasis pustulosa – occurrence of pustules (pustule) in the course of acute psoriasis; 0.5-2.5% of cases.
Sex ratio: men and women are equally affected.
Frequency peak: psoriasis vulgaris type I first appears predominantly before the age of 40. Psoriasis vulgaris type II manifests after the age of 40 (late type).
The prevalence (disease frequency) is 1-2% (in western industrialized countries). In childhood, the prevalence of psoriasis vulgaris increases linearly from 0.12% in infants to 1.2% in 17-year-olds.
Course and prognosis: Psoriasis progresses in episodes and is considered a benign skin disease. It is not curable, but can be treated well with adequate pharmacotherapy (drug treatment). Psoriasis vulgaris type I tends to be more severe, while type II takes a milder course. 90% of patients develop a chronic course.
Psoriatic arthritis (PsA; inflammatory disease of the joints caused by psoriasis) affects about 5-15 % of all psoriasis patients; sometimes it precedes the skin disease; about 66 % of psoriatic arthritis patients have nail psoriasis.
The median age at death was 74.4 years for mild psoriasis and 72 years for severe psoriasis (76.5 years for controls).
Comorbidities (concomitant diseases)
- Obesity (overweight)1+2
- Arterial hypertension (high blood pressure)1+2
- Arthritis (inflammation of the joints)1 – in children as juvenile arthritis (JIA); may precede psoriasis by months to years
- Bronchial asthma (1.38 times more common).
- Chronic inflammatory bowel disease (IBD), e.g. Crohn’s disease about two times more often.
- Diabetes mellitus type 2 – average risk of diabetes of psoriasis-free patients 1.21 and psoriasis patients 1.64
- Liver cirrhosis (irreversible damage to the liver leading to gradual connective tissue remodeling of the liver with impairment of liver function; 14.1% of all patients with severe psoriasis)
- Metabolic changes such as hyperlipoproteinemias (dyslipidemia)1+2.
- Psychiatric disorders1+2: As a result of skin appearance and social exclusion, anxiety disorders* , depression* as well as substance abuse* are significantly increased
- Rheumatoid arthritis (about 4 times more often).
- Celiac disease (4.1%); a gluten-free diet also shows beneficial effects on skin lesions
1Comorbidities in childhood2 Comorbidities independent of age.