γγDon’t assume that any bald spot that you suddenly find is baldness. The full name of baldness is “patchy baldness”, commonly known as “ghost shaving”. It is a sudden discovery of one or several round or oval-shaped patches of hair loss of varying sizes on the scalp, with a normal scalp and no discomfort. To diagnose alopecia areata, the following diseases should be excluded: 1. Venereal diseases: Syphilis II can show “worm-like” hair loss, with irregularly shaped spots. Patients may also have a second-stage syphilis rash and positive syphilis serology tests. 2. Hair plucking fetish: This is a psychosomatic disorder in which the patient always has an urge to pluck, pull, cut or scrape the hair, resulting in hair loss spots with strange shapes, but the patient often does not admit it to himself.γγ4, scarring alopecia: there are many causes, including tinea capitis caused by local fungal infection. It is now rare and mainly involves children. Patients have round hair loss patches on the head with hair breakage or desquamation and pus scabs, which may have a foul odor. It can be cured by anti-fungal treatment. Folliculitis, boils or abscesses formed by bacterial infections can also form scarring alopecia if they destroy the hair follicles. Other causes include lupus erythematosus, which shows limited erythema, atrophic scarring and pigmentation changes, and may show follicular keratosis; lichen planus, which shows purplish red spots, keratotic follicular papules and hair loss on the scalp; skin tumors, etc.