Psoriasis is an inflammatory, systemic skin disease characterized by red, scaly lesions that may involve portions of the body or nearly the entire body. A genetic predisposition is indicated by the number of psoriatic patients who have relatives with psoriasis. While the underlying cause of psoriasis is still unknown, considerable evidence points to dysfunction of the immune system as a cause or contributing factor.
While psoriatic lesions can appear anywhere on the body, the scalp is one of the most frequent sites. The scalp may be the first site affected in children and young adults, and in some persons it remains the only site affected.
Psoriasis has many levels of severity and many different clinical features ranging from shedding of grayish scales to pustular eruptions. Severe forms of psoriasis may be associated with other inflammatory conditions, especially psoriatic arthritis and inflammatory bowel disease (see What is Inflammation?).
Psoriasis of the scalp usually has a distinctive appearance of inflamed skin overlain with silvery scales. In severely progressive disease the psoriatic lesions may merge into a solid mass of scales over the entire scalp, with temporary or permanent hair loss. Psoriasis of the scalp and seborrheic dermatitis of the scalp have many features in common and may be confused unless properly diagnosed. Atopic dermatitis, an inflammatory, extremely pruritic skin disease, may also resemble psoriasis; scalp involvement in atopic dermatitis is more frequent in infants and children but does occur also in adults. Because treatment is different for each of these diseases, correct diagnosis is essential to appropriate treatment.
Authoritative information about psoriasis and specifically psoriasis of the scalp is available at:
Diseases and Disorders of the Scalp