Psoriasis is a recurring, non-contagious skin disorder that is characterised by raised, thickened patches of red skin covered with silvery white scales.
Psoriasis originates in the immune system. The key immune system trigger is the activation of T-cells, a type of white blood cell. Once activated, these cells release cytokines, which are the chemicals used by the immune system to communicate messages. In psoriasis, these cytokines tell skin cells to multiply and mature at an accelerated rate, resulting in thickening of the skin. The redness results from the increased blood supply required for the increased growth of cells.
Psoriasis is worsened by stress, alcohol and certain medications
Types of Psoriasis
common type in which there are large patches of red skin with silvery-white scales.
small patches, usually less than 1cm in diameter.
Psoriasis occuring in the body folds such as armpits and groins
almost the entire body is red with Psoriasis
small pustules (pus filled areas) are scattered throughout the body
Sites of Psoriasis
Common areas of involvement include:
flexures - armpits, groins and gluteal cleft (groove between buttocks). Type of psoriasis where the flexures are predominantly involved is called flexural psoriasis.
Nail changes in Psoriasis
The nail changes of psoriasis cannot be distinguished from a fungal infection by just looking at the nails. For this reason, nail clippings need to be sent to the laboratory for analysis. Treatment for fungal infection should be administered only if the nail shows fungus.
Topical (Applied on the skin)
2% Ung acid sal
this medication peels the thickened skin and restores normal skin thickness
reduces the rapid growth of skin cells
Calcipotriol / Betamethasone combination (Dovobet)
effective in restoring normality in psoriasis areas
Clobetasol shampoo (Clobex). This is a strong topical steroid preparation and its use on the scalp must be limited to 2 weeks at a time.
Home care phototherapy
New treatments for Psoriasis (Biologics)
The biologics are a new line of psoriasis treatments which target specific parts of the immune system. They therefore are expected to have fewer side effects than existing treatments. Unlike other systemic drugs, the biologics are administered by injection.
Infliximab is given intravenously in the doctors office. Initial treatment is administered at weeks 0,2 and 6. Thereafter, treatment is given at 8 week intervals.
This biologic has been approved for the treatment of psoriatic arthritis and is undergoing final testing in patients with skin psoriasis. Intitial studies have shown that half the patients achieved more than 70% clearance and that 70% of patients achieved 50% clearance. It is administered by subcutaneous injection twice weekly. Patients can be taught to administer the treatment at home, much like injecting insulin at home for diabetes.
Self injected subcutaneously, 80mg followed by 40mg a week later, then 40mg every fortnight.
Given by subcutaneous injection at week 0, 4 then once every 3 months. Patients weighing less that 100kg get 45mg and those over 100kg receive 90mg per injection.
The Psoriasis Advisory Board of South Africa has put together a set of guidelines for the management of Psoriasis. This has recently been published in the South African Medical Journal (SAMJ)
Psoralen is taken orally 2 hours before exposure to UVA light. Treatment is administered three times a week for 7 weeks - a total of 21 treatments.