Lip round or oval erythematous mucosal lesions preferably occur on the lower lip lip red, round or oval erythematous, slightly depressed in the center, slightly elevated with dark red edges, and white radiating patterns around the lesion. The lip lesions often go beyond the red edge of the lip and involve the skin, making the mucosal skin boundary blurred. There is hyperpigmentation or hypopigmentation around the lesion area. The skin lesions are usually found on the head and face and are characterized by scaling, dilated capillaries, follicular keratin plugs, hyperpigmentation and/or hypopigmentation, and scar formation. Laboratory tests: Leukocyte antigen (HLA): detection of HLA helps in the diagnosis, typing, and prognosis of certain diseases, and can be done by serum method to determine A, B, and C site antigens, and by mixed lymphocyte culture method to determine D and DR antigens. Normal value: Negative blue dead cell count <20%. Precautions I. Precautions before the blood draw: 1. Do not eat too greasy, high-protein food the day before the blood draw, and avoid drinking large amounts of alcohol. The alcohol content in the blood will directly affect the test results. 2, not fasting examination. 3, blood should be relaxed when drawing blood to avoid vasoconstriction caused by fear, increasing the difficulty of blood collection. Second, after the blood draw should be noted: 1, after the blood draw, the need for local pressure at the needle hole for 3-5 minutes to stop bleeding. Note: Do not rub, so as not to cause subcutaneous hematoma. 2. The duration of pressure should be adequate. The clotting time varies from person to person, and some people need a slightly longer time to clot. So when the skin surface does not seem to bleed immediately stop compression, may not completely stop bleeding, and blood seepage to the subcutaneous cause bruising. Therefore, longer pressure is necessary to stop bleeding completely. If there is a tendency of bleeding, the pressure time should be extended. 3. If local bruising occurs, apply warm towels with wet compresses after 24 hours to promote absorption. 3. Before the test, please inform the doctor of the recent medication and special physiological changes Examination procedure: the number of immune cells detection method. Other auxiliary tests: elevated IgG or positive antinuclear antibody. Individual cases of LE positivity and liver dysfunction.