Psoriasis derives its name from the Greek word for 'itch'. It is a common, genetically determined, inflammatory and proliferative disease of the skin. It is characterized by a rapid buildup of rough, dry, dead skin cells forming thick scales.  Normally, it takes about a month for new skin cells to move from the lowest layer of  skin, where they form, to the outermost layer, where they die and scale off in flakes. In psoriasis, the life cycle of skin cells speeds up, resulting in a multitude of dead cells on the outermost layer of  skin.

Incidence and Prevalence

The overall prevalence of psoriasis is about 1-3 %. It can occur suddenly at any age, but the onset is usually gradual and begins between ages 15 and 35. Psoriasis affects both sexes and all races.

Americas: 1-2 %. Rare in American blacks and absent in Red Indians.

South America: 0.97%

Germany: 1.3%

Great Britain: 1.6%

Denmark: 1.7%


West Africa-Rare


Eskimos: Very Low


The evidence that psoriasis may be inherited is beyond doubt, and rests on population surveys, twin and other family analyses and HLA studies. There has, however, been controversy over the mode of inheritance and researchers haven't yet been able to identify the gene or genes responsible for psoriasis.
It is common for psoriasis to run in families;approximately one-third of patients with psoriasis have a family member with the same condition.

Several other factors are important in provoking or exacerbating psoriasis;

  1. Trauma; psoriasis worsens in areas of skin trauma (Koebner's phenomenon), so don't pick, scratch, or scrub the lesions and scales!

  2. Infection;  acute streptococcal infection precipitating guttate psoriasis.

  3. Endocrine factors

  4. Sunlight; although generally is beneficial for psoriasis, but it's better to avoid strong sunlight always!

  5. Metabolic factors; hypocalcemia

  6. Drugs; especially lithium, beta blockers and antimalarials . Also clonidine, iodides, glibenclamide, and tetracycline may exacerbate psoriasis

  7. Psychogenesis factors

The role of food visa viz psoriasis is controversial. Red meats are generally considered to exacerbate psoriasis. A few shellfish may stimulate an acute exacerbation while, as a whole fish is considered beneficial in psoriasis. Fish oils containing essential fatty acids have been found to be effective in many patients, though conclusive evidence is still awaited.

Clinical features

Psoriasis has several clinical expressions, but the most frequent type is psoriasis vulgaris, which occurs as chronic scaling papules and plaques in characteristic sites of the body, largely related to repeated minor trauma: scalp, elbows, forearms, lumbosacral region, knees, but usually not on the face.

Other variants of psoriasis are; erythrodermic psoriasis, generalized psoriasis, guttate psoriasis and pustular psoriasis.

Psoriasis only rarely affects general health apart from arthritis. Itching is usually mild. Once the problem starts, it usually continues although it may get better or worse over time and even seem to disappear for prolonged periods.

Psoriatic Arthritis

About 10 percent of people with psoriasis develop psoriatic arthritis. Commonly they are adults in their 20s, 30s and 40s. Psoriatic arthritis is not accompanied by rheumatoid-type nodules, and has been classified into five clinical groups which often overlap:

1. Predominantly peripheral mono- or asymmetrical oligoarthritis

2. Predominantly distal interphalangeal arthritis

3. Predominantly symmetrical, rheumatoid-like arthritis

4. Arthritis mutilans

5. Predominantly axial arthritis


One of the things that make psoriasis so difficult to control is its wide variation in type, severity and response to treatment. There are some myths and facts about psoriasis that you should know;

  1. At present there is no cure for psoriasis but it can often be completely cleared for periods of months or even years.

  2. Every psoriatic patient presents an individual problem. Treatment depends upon age, sex, occupation, personality, general health, intelligence and resources as well as the type, extent, duration and natural history of the disease.

  3. Psoriasis does not appear to shorten a person's life.

  4. Psoriasis itself will not cause the hair to fall out.

  5. There is no scientific evidence that homeopathic treatments are effective for treating psoriasis.

Topical Treatments

Systemic Treatments

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