Dr Cameron Kennedy, consultant dermatologist at Bristol Royal Infirmary in Britain, said unlike other skin conditions such as eczema and acne, high humidity in Hongkong would not adversely affect psoriasis, but that exposure to the sun as well as regularapplications of effective ointments would help control the condition.

''It depends on the severity of the psoriasis, but in a number of cases we have seen the new topical drugs provide significant relief,'' he said.

One of the new medications, Daivonex, is made by Leo Pharmaceutical Products in Denmark, and is considered a major advance in treatment of psoriasis, particularly for mild to moderate sufferers.

The active ingredient in the medication, Calcipotriol, is a synthetic form of vitamin D and controls the growth of affected skin cells.

The second treatment, Cutivate, is a topical application manufactured by Glaxo and is only available in the US. An application for distribution in Hongkong has been made to the Department of Health, and the company is hoping to have it on the market soon.

Containing fluticasone, - milder than most other steroids - Cutivate would be better suited for children, said Dr Kennedy.

Modern science has yet to come up with a long-term cure to combat a skin condition that can often destroy the self-confidence of people who suffer from it.

Psoriasis occurs when an underlying abnormality causes cells in the upper layer of skin to reproduce about 10 times faster than normal. The new skin cells accumulate and form thick patches, covered with dead flaking skin.

Inflammations can occur on the face, neck, elbows, knees, scalp and trunk, and are often covered by rough, silvery scales and can crack and bleed, leaving many sufferers too ashamed and embarrassed to go out in public.

The disease can develop at any time; a newborn baby is as likely to get it as a man in his 80s, although it starts more frequently between the ages of 15 and 45, particularly around puberty and menopause, and attacks can be triggered by physical illness and emotional stress.

Previous treatments have included over-the-counter creams, powerful oral drugs, steroid creams, coal tar and ultra-violet light radiation, but some side-effects have been reported.

The vice-chairman of the Hongkong Society of Dermatology, Dr Ronald Leung, said moderate exposure to natural sunlight was a recommended treatment, and could help in alleviating symptoms of the disease.

''There is no doubt that psoriasis is associated with genetic make-up, but a significant portion of people respond to light therapy and it can even clear up with sunlight in the summer,'' he said.

Dr Leung said trial studies on the new treatments were so far preliminary and that further tests would have to be undertaken to assess efficacy, particularly with children.

''But I can categorically say there is no long-term cure available. Psoriasis is undulating and has its own course. It may flare up and then it will get better but while there are a number of measures to control it, a cure has still not been achieved. And nobody is exempt from it,'' he said.

The disease could be severely disfiguring, he said.

''There is a lot of social pressure, so there are psychological repercussions and, apart from the cosmetic point of view, if you have psoriasis, you are more likely to develop joint problems as well.'' Dr Leung said the condition was difficult to control, and therefore many levels of therapy would apply, ranging from simple hydro-cortisone creams to powerful oral drugs.

But many people believe psoriasis is either contagious or is linked to leprosy or venereal disease, a misconception which heightens the social stigma attached to the condition.