Symptoms of the patient’s perianal air masses may be caused by urticaria, drug dermatitis, menstrual rash and other diseases. 1. Urticaria: Urticaria is an allergic disease, which is a kind of limited edema reaction appeared by the expansion of small blood vessels of skin and mucous membrane and the increase of permeability. Its onset may be caused by a variety of food, drugs and other factors stimulation, mainly manifested in the wind, the size and shape of the wind of different, bright red or pale white, with obvious itching. 2. Drug dermatitis: drug dermatitis, also known as drug rash, is an inflammatory reaction of the skin and mucous membranes triggered by drugs entering the human body through the oral, injectable, topical absorption, etc., which is roughly caused by drug overdose, intolerance, idiopathic, side effects, allergic effects, and so on. The main manifestations of the skin is a rash, with itching, pain, hyperpigmentation and other symptoms, serious cases may also be accompanied by internal organs damage. 3. Menstrual rash: menstrual rash occurs in female patients, it is a kind of rash skin disease related to menstrual cycle, patients may appear in the limbs and trunk area of erythema, papules, bullae, blisters, blisters and other polymorphic skin lesions, accompanied by itching. In addition, insect bite dermatitis, hookworm dermatitis, lice disease and other diseases may also cause perianal eruption, it is recommended that patients seek medical treatment in a timely manner, strictly comply with the medical prescription of medication, and actively cooperate with the doctor’s treatment, to avoid aggravation of the condition.