Red patches on the body are painless and itchy, which may be caused by purpura, lupus erythematosus, hemangioma, and squamous cell carcinoma in situ.
1. Purpura: allergic purpura, idiopathic thrombocytopenic purpura can cause subcutaneous capillary rupture, resulting in skin bruises, may cause symptoms similar to red patches on the body, painless and itchy.
2. Lupus erythematosus: an autoimmune disease that causes red patches of skin, some of which are accompanied by scales, usually without itching or pain.
3. Hemangioma: it is a tumor of vascular origin with abnormal proliferation of vascular endothelial cells, which can cause congestive abrasion-like, or capillary dilatation plaques, and also lead to symptoms similar to red plaques on the body, which are painless and itchy.
4. Cell carcinoma in situ: it may be related to long-term exposure to arsenic, chronic sunlight damage, immune function inhibition, or HPV infection, manifested as isolated, well-bordered dark red patches or plaques, with no obvious self-conscious symptom and occasional itching or pain.
Red patches on the body do not hurt or itch, there may be other reasons, it is recommended that the patient promptly to the hospital, to clarify the cause of the disease, and follow the doctor’s instructions for treatment.