Hair loss of a piece may be due to pemphigus, syphilitic alopecia, ringworm and other causes. 1. Patchy baldness: it is an autoimmune-related non-scarring hair loss disease, clinically manifested as a sudden appearance of a varying number of round or oval hair loss, with smooth skin in the affected area, free of inflammation, scaling and scarring. 2. Syphilitic alopecia: when the disease progresses to the second stage of syphilis, the skin and mucous membrane are damaged, and the syphilis spirochete can invade the hair follicle, which can cause small and scattered patchy alopecia. 3. Tinea capitis: hair and scalp infected by ringworm bacteria can appear tinea capitis, clinical manifestations of single or multiple alopecia patches, often accompanied by scales, severe scarring, or even permanent hair loss. When a piece of hair loss, it is recommended to go to the dermatology department, after the relevant examination under the guidance of the doctor’s diagnosis and treatment.