Dr. Cole is board certified in dermatology. He obtained his BA degree in bacteriology, his MA degree in microbiology, and his MD at the University of California, Los Angeles. He trained in dermatology at the University of Oregon, where he completed his residency.
Dr. Shiel received a Bachelor of Science degree with honors from the University of Notre Dame. There he was involved in research in radiation biology and received the Huisking Scholarship. After graduating from St. Louis University School of Medicine, he completed his Internal Medicine residency and Rheumatology fellowship at the University of California, Irvine. He is board-certified in Internal Medicine and Rheumatology.
Psoriasis is an inflammatory disease of the skin that is estimated to affect about 2.2% of the adult population. Some people may have a genetic predisposition to psoriasis. The genes affected seem to be involved with control of the immune system. Psoriasis appears as red scaling, slightly raised bumps (papules) that combine to form plaques. Psoriasis classically appears on the elbows and knees, but it can affect any part of the skin. The scalp is also characteristically affected in many people with psoriasis. Like psoriasis anywhere, scalp plaques produce excess scale and can itch. Severe disease can cause a loss of scalp hair, which usually will return if the disease can be controlled.
Picture of scalp psoriasis. Source: iStock.com.
What is the cause of scalp psoriasis?
It is generally accepted that scalp psoriasis, like all psoriasis, is related to genetic defects that affect certain parts of the immune system. There are undoubtedly environmental factors that trigger its initial development in genetically predisposed individuals. The notion that "emotional stress" plays a causal role or at least exacerbates psoriasis has been difficult to prove. There is no question, however, that psoriasis of the scalp can be an extremely stressful experience.
Psoriasis appears as a small bump, a papule, surmounted by scale. When these papules coalesce, a plaque is formed that is often covered by thick layers of horny scale. When this scale is shed, it appears as dandruff, which can be quite unsightly. Scratching these plaques, either because of itching or because of the impulse to remove it, is a very poor idea because of what is called the Koebner phenomenon (also known as the Koebner response or isomorphic response). This may cause psoriasis to develop in areas of inflammation and trauma. Scratching off the scale will only make things worse. Occasionally, seborrheic dermatitis of the scalp can be confused with psoriasis since both can produce excess scale and can itch.
Psoriasis commonly occurs on the scalp, which may cause fine, dry, scaly skin or heavily crusted plaque areas. This plaque may flake or peel off in clumps. Scalp psoriasis may resemble seborrheic dermatitis, but in that condition the scales are greasy and not dry.