A lot of bumps on the buttocks especially itchy may be due to urticaria, eczema, ringworm and other diseases. 1. urticaria: the cause is mainly related to food allergies, infections, autoimmune and other factors, there will be a raised skin edematous wind, accompanied by itching. 2. Eczema: the cause is mainly related to genetic, immune abnormalities, metabolic diseases, chronic infectious lesions and other factors, there will be erythema, papules, papules, intense itching and other symptoms. 3. Ringworm: It is mainly caused by various dermatophyte infections, and is prevalent in the buttocks. It is mainly characterized by ring-shaped lesions, papules, itching and other symptoms. There are many reasons that lead to a lot of bumps on the buttocks especially itchy, and it is recommended that patients go to the hospital to clarify the cause of the disease.