Circular hair loss (alopecia areata)

Circular hair loss, medically known as alopecia areata, is a common form of hair loss in which circular bald patches form on one or more areas of the head. Around one to two percent of the population are affected in the course of their lives. The condition can occur at any age, but often begins in childhood or young adulthood. Men and women are affected equally often. The cause is an autoimmune reaction in which the body’s own immune system mistakenly attacks the hair roots and causes inflammation. The hair falls out, but the hair roots remain intact so that the hair can, in principle, grow back. Why the immune system is misdirected is not fully understood. Genetic factors play a role, as the disease runs in families. Psychological stress is also discussed as a possible trigger. The disease manifests itself in the form of suddenly appearing, usually circular bald patches on the head. The skin in these areas is smooth, not reddened or scaly. At the edge of the bald patches there are often so-called exclamation mark hairs, which become thinner towards the end. In severe cases, all the hair on the head may fall out or even the entire body hair. The fingernails can also be affected and show pits or grooves. The diagnosis is made clinically based on the typical appearance. A hair-pulling test can be carried out, in which hair can be easily pulled out from the edges of the bald patches. In unclear cases, a scalp biopsy can be performed. Treatment is difficult as there is no therapy with guaranteed success. Small areas can be treated with a wait-and-see approach, as the hair often grows back on its own. Solutions or creams containing cortisone can be applied locally. In the case of extensive infestation, cortisone injections into the scalp or systemic cortisone therapy can be considered. The prognosis varies greatly: for many sufferers, the hair grows back within a year, for others the disease is chronic with recurring relapses.