In a school-age child with RLQ pain, the commonest mimic of appendicitis is mesenteric lymphadenitis, often after a recent viral or respiratory infection. Intussusception is the tempting choice, but it typically affects infants (around 1 year old), with red-currant-jelly stool and a sausage-shaped mass. Renal colic, malrotation and Wilms tumour are much less likely in this setting.