PSORIASIS

Psoriasis is a chronic recurrent, inherited, non-infectious skin disease
caused by an abnormally fast turnover of the epidermis. The turnover may
be up to 40 times the normal and as a result the epidermis is not able to
develop normally. All layers become too thick and the most obvious one
is the horny layer, the outer layer of the skin. The skin is red, inflamed,
and the scales are thicker than normal. They produce a so-called candlewax
phenomenon: when you scratch such a patch it becomes silverywhite.
Psoriasis also displays a Koebner phenomenon, i.e. it appears in
traumatised skin. Classical psoriasis occurs on the scalp, the extensor
areas of extremities (esp. elbows, knees), the umbilicus and the buttocks.
Finger- and toenails may show pitting, thickening of the nailbed or distal
onycholysis (brownish oil-like changes on the distal nail where the nail is
detached from the nailbed). Palms and soles may also show thickening;
callus, scales and cracks. Treatment is often effective but you can never
cure the patient of the disease as such. It may always recur, after weeks,
months or years. Psoriasis may flare up after an infection (flu, angina) or
drug use (e.g. antimalarial drugs, beta blockers, lithium). There is also a
pustular psoriasis and an inverse form with lesions in skin folds rather
than extensor areas, the latter may be difficult to distinguish from seborrhoic
eczema.
Psoriatic arthritis of the small joints of the hands and feet occurs in 5-
10% of patients. The arthritis may be mutilating and eventually become
widespread.
Management of psoriasis
- Explain to the patient the recurrent nature of the disease.
- Salicylic acid 2-10% ointment twice daily to reduce scaling.
- Coal tar 5-10% ointment or sulphur 5% in coal tar 5-10% ointment nightly.
- Moisturise (vaseline, urea 10% ointment or cream) and expose to sun. In psoriasis
coal tar ointment may be tried in combination with sunlight.
- Salicylic acid and coal tar should not be applied on body folds unless the skin is
dry and thickened. They can be mixed together as ointments, or with zinc paste.
- In body folds sulphur added to a mild steroid cream is often effective.
- A strong topical steroid once or twice daily, cover with salicylic acid 2-10% ointment
if necessary.
- Urea 10% cream or ointment as an emulsifier, aqueous cream in folds.
- Treat any superinfection with betadine or antibiotics if necessary.
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- Psoriatic arthritis: NSAID’s e.g. ibuprofen 400 mg 4-6 x daily, indomethacin 75-100
mg daily, naproxen 500-750 mg daily or salazosulphapyridine 250 - 500 mg twice
daily.
- Methotrexate is often effective in severe and arthropathic psoriasis and may be
used in HIV infected patients.