Echogenic kidneys, target or doughnut sign in case of intussusception. IgA vasculitis has also been shown to cause massive scrotal oedema, and can be a source of severe pain in young boys.
Henoch-Schönlein purpura echocardiography or ultrasound
Hemolytic-uremic syndrome echocardiography and ultrasound
Henoch-Schönlein purpura physical examination
Kawasaki disease echocardiography and ultrasound
Loefflers syndrome chest x ray
Behçet's disease echocardiography or ultrasound
Goodpasture syndrome chest x ray
Adult-onset Still's disease physical examination