Alopecia barbae causes one or more smooth bald patches in beard-bearing skin. It is usually considered a form of alopecia areata, where the immune system targets hair follicles. The skin is often normal-looking rather than scaly or scarred, although itching or tingling may occur. It can regrow spontaneously, recur, or spread to other areas. Treatment options may include observation, topical therapies or steroid injections, depending on patch size, symptoms and patient preference.
BAD alopecia areata: https://www.bad.org.uk/pils/alopecia-areata ; DermNet alopecia areata: https://dermnetnz.org/topics/alopecia-areata