A bald patch on the scalp is considered to be related to conditions such as pemphigus vulgaris, tinea capitis, and scarring alopecia. 1. Pemphigus vulgaris: It is a psychogenic factor-led, autoimmune-related, non-scarring hair loss disease. Typical manifestation is the sudden appearance of round or oval, 1-10 cm in diameter, varying number of hair loss areas with clear boundaries, smooth skin in the affected area, without inflammation, scaling and scarring. There are generally no self-conscious symptoms. 2. Tinea capitis: Tinea capitis is an infectious disease caused by fungi such as dermatophytes infecting the scalp hair. It is mainly characterized by redness, scaling, itching and alopecia areata on the scalp. 3. Scarring alopecia: such as scleroderma, lupus erythematosus and so on when the scalp is involved, damage to the scalp hair follicles, resulting in hair follicles shrinking and fading, so that alopecia areata spots appear. The scalp often presents as atrophic scarring, which eventually manifests itself as a bald patch on the scalp. A bald patch on the scalp is considered to be related to skin problems, and it is recommended to visit the dermatology department of the hospital to find the cause.