Psoriasis is a chronic inflammatory skin condition characterized by clearly defined, red and scaly plaques (thickened skin). It is classified into several subtypes.
Psoriasis affects 2–4% of males and females. It can start at any age including childhood, with peaks of onset at 15–25 years and 50–60 years. It tends to persist lifelong, fluctuating in extent and severity. It is particularly common in Caucasians, but may affect people of any race. About one third of patients with psoriasis have family members with psoriasis.
Psoriasis usually presents with symmetrically distributed, red, scaly plaques with well-defined edges. The scale is typically silvery white, except in skin folds where the plaques often appear shiny and they may have a moist peeling surface. The most common sites are scalp, elbows and knees, but any part of the skin can be involved. The plaques are usually very persistent without treatment. Itch is mostly mild but may be severe in some patients, leading to scratching and lichenification (thickened leathery skin with increased skin markings). Painful skin cracks or fissures may occur. When psoriatic plaques clear up, they may leave brown or pale marks that can be expected to fade over several months.
Certain features of psoriasis can be categorized to help determine appropriate investigations and treatment pathways. Overlap may occur.
- Streptococcal tonsillitis and other infections
- Injuries such as cuts, abrasions, sunburn (koebnerized psoriasis)
- Sun exposure in 10% (sun exposure is more often beneficial)
- Excessive alcohol
- Stressful event
- Medications such as lithium, beta blockers, antimalarials, nonsteroidal anti-inflammatories
- Stopping oral steroids or strong topical corticosteroids.
Patients with psoriasis are more likely than other people to have other health conditions listed here.
- Inflammatory arthritis “psoriatic arthritis” and spondyloarthropathy (in up to 40% of patients with early onset chronic plaque psoriasis)
- Inflammatory bowel disease (Crohn disease and ulcerative colitis)
- Uveitis (inflammation of the eye)
- Celiac disease
- Metabolic syndrome: obesity, hypertension, hyperlipidemia, gout, cardiovascular disease, type 2 diabetes
- Localized palmoplantar pustulosis, generalized pustulosis and acute generalized exanthematous pustulosis
Patients with psoriasis should ensure they are well informed about their skin condition and its treatment. There are benefits from not smoking, avoiding excessive alcohol and maintaining optimal weight. Which treatment is selected may depend on body site, extent and severity of psoriasis. Mild Psoriasis is generally treated with topical agents alone. More severe cases of psoriasis may be treated with phototherapy, systemic medications or some combination of the two.