Psoriasis is a common skin condition characterized by patches of red, thickened, and scaling skin. It often affects the elbows, knees, and scalp but may be found anywhere. The disease usually appears between the ages of 10 and 30, tends to run in families, and affects both men and women. Several forms are recognized and the manifestations may vary in each individual with time. The cause of most forms is unknown, although one form (guttate psoriasis) may be caused by a streptococcal infection (see Streptococcus), such as tonsillitis.

 

Symptoms and types of psoriasis

In psoriasis, new skin cells are made about ten times faster than normal. The excess cells accumulate, forming thickened patches with dead, flaking skin. Sometimes, there is also a painful swelling and stiffness of the joints (see arthritis). Psoriasis tends to recur in attacks, which may be triggered by factors such as emotional stress, skin damage, and physical illness.

 

There are different forms of the disease, the most common of which is discoid, or plaque, psoriasis, in which patches appear on the trunk, limbs, and scalp. Another type, guttate psoriasis, occurs most often in children, and consists of many small patches that develop over a wide area of skin. Pustular psoriasis is rare, and is characterized by pustules (small blisters containing pus) over part or all of the body.

 

Treatment

In most cases of psoriasis, the condition can be improved with topical treatments, such as those containing corticosteroid drugs, coal tar, calcipotriol, and other vitamin D analogs. Other treatments include diathranol ointment, PUVA, and drugs such as methotrexote. Psoriasis is usually a long-term condition.