The characteristic clinical sign of alopecia areata is

Ans) a (exclamutory marl-: hair) Ref Rook "s text hook of dermatology 7th ed page no 63,42The onset of alopecia areata may be at any age, peaking between the second and fourth decades. The sex incidence is probably equal. The characteristic initial lesion is a circumscribed, totally bald, smooth patchIt is often noticed by chance by a parent, hairdresser or friend.The skin within the bald patch appears normal or slightly reddened. Short, easily extractable broken hairs, known as exclamation mark hairs, are often seen at the margins of the bald patches during active phases of the disease,ie gradual thinning of broken stub towards the base which consists of an unpigmented telogen club