There are many causes of large bumps on the thighs of a 19-month-old child, such as papular urticaria, folliculitis, herpes, atopic dermatitis and so on. 1. papular urticaria: 19-month-old child thighs with big bumps need to be considered as papular urticaria, usually occurs in the summer, due to mosquito bites caused by pimples, accompanied by obvious itching. 2. Folliculitis: poor local skin hygiene on the thighs, improper diet, etc., can induce folliculitis, which can lead to the phenomenon of 19-month-old children with big bumps on the thighs. 3. Herpes: Herpes virus infection in children can lead to the phenomenon of 19-month-old children with big bumps on the thighs, and the herpes will break out in the later stage, resulting in the formation of ulcers. 4. allergic dermatitis: the child came into contact with allergens, resulting in allergic skin reactions, may also cause the phenomenon of 19-month-old child thighs with big bumps, accompanied by itching. 19 months the child thighs with big pimples of many reasons, after the symptoms are recommended to go to the hospital in a timely manner, in accordance with the doctor’s instructions for standardized treatment, not to private treatment, so as not to lead to adverse consequences.