Alopecia and hair disorders in children — structured clinical encounter

An eight-year-old girl has a three-week history of a coin-sized, completely bald, smooth patch behind the left ear with a few tapering exclamation-mark hairs at the edge and no scale or lymphadenopathy. You are the paediatric registrar working through assessment, confirmation, the autoimmune associations, the stepwise management and the prognostic features, then a later scenario of a twelve-year-old with an irregular patch of varying-length hairs on a normal scalp, and a question on distinguishing a scaly bald patch of tinea capitis.