The back of the head generally refers to the occiput, occipital hair loss for a piece of occipital alopecia, may be baldness, seborrheic dermatitis, rickets and so on. 1. Patch baldness: Patch baldness is a psychogenic factor-led, autoimmune-related non-scarring hair loss disease, the cause of which is not yet completely clear, and is currently believed to be related to genetics, mental and emotional stress, endocrine disorders, immune inflammation and other factors. 2. Seborrheic dermatitis: it may be related to excessive skin oil or Malassezia infection, resulting in chronic inflammation of the occipital skin, follicular papules and desquamation, etc., and hair follicles have been destroyed, causing localized hair loss in the occipital area. 3. rickets: this is common in infants and young children, due to abnormalities in the regulation of sweat leading to infants and young children sweating, head and pillow sweating stimulation caused by frequent friction between the head and pillow, resulting in occipital hair loss. Cause the back of the head lost a piece of hair may also have other reasons, it is recommended to consult a doctor in a timely manner, with the help of a doctor to clarify the cause, and targeted treatment or treatment.