Test your diagnostic skills in our regular dermatology quiz. What is causing these recurrent itchy nodules?
A 15-month-old boy presents with recurrent itchy lesions on his legs (Figure). He scratches them and they rapidly become excoriated and infected. It is summer time, and his mother says he has been bitten by mosquitoes on several occasions. She has noticed that these mosquito bites often develop a large wheal that takes several days to resolve.