Polymorphic heliotrope is an acquired, idiopathic, intermittently recurring photosensitive skin disease. The pruritic rash occurs a few hours or days after sun exposure and completely resolves 1-6 hours or more after sun exposure is stopped, leaving no scarring after healing. It can recur for many years and then disappear spontaneously. The disease is currently considered to be a sun-induced late-onset metabolic skin disease, related to genetics, endocrine, trace elements, metabolic changes, etc. Clinical manifestations: 1. Onset in spring and summer, usually in young and middle-aged women. 2. It occurs on the face, the back of the neck, the V-shaped area in front of the neck, the back of the hands and the extended side of the forearm and other exposed areas. The lesions occur between 2 hours and 5 days after sun exposure, while hair and clothing covered areas are not involved. The lesions are polymorphic, commonly with small papules and papules, but can also be manifested as edematous erythema, large papules or plaques mossy. It can be divided into papular herpes type; papule type; itchy rash type; erythematous edema type; mixed type 5. 4, there is a clear seasonal onset, long-term recurrence can lose seasonality, and the rash can be extended to non-exposed areas. Pruritus is obvious. Mostly no systemic symptoms. 5, 15% of patients have a family history of photosensitivity. 6. Abnormal photoexcitation test: rash is induced by UVA or UVB irradiation of the skin. Differential diagnosis: 1, sunburn: an acute skin reaction with a short course; 2, seedpox-like blistering disease: erythema, dark red papules and papules of soy size occur after sun exposure on the back of the nose, cheekbones, ear flanks, and back of the hands, with an umbilical concavity in the center of the blister, forming a vesicle. It leaves a depressed atrophic scar after fading. After puberty, the condition remits; 3, porphyria (erythropoietic protoporphyria): the disease is autosomal dominant, with a family history. It develops before puberty, with burning sensation and erythema of exposed skin after sun exposure, red edematous patches in the acute phase, and superficial wax-like scarring in the chronic phase. 4. Lupus erythematosus (DLE and SCLE): DLE lesions have adherent scales and scarring, while SCLE rash is widely distributed and often accompanied by systemic symptoms and abnormal immune indicators. The pathological histology of lesions is characteristic. Treatment plan 1, general treatment: avoid sun exposure, apply shading agents when going out; susceptible patients can undergo preventive phototherapy before the onset of the disease in spring every year, starting with a small dose of ultraviolet radiation, and gradually increasing the dose to improve the tolerance of the skin to light. 2.Topical treatment: glucocorticoid topical, such as Eudragol, Erosone, Pirenzone, etc.; 0.5%-1% indomethacin cream, 2-3 times a day. 3.Systemic treatment: oral antihistamines such as epalrestine, loratadine, levocetirizine; glucocorticoids such as prednisone, dexamethasone; tretinoin; hydroxychloroquine, etc. 4. Chinese herbal medicine is given according to the situation to remove wind, clear heat, cool blood, and de-liver the liver.