[A boy with pain in the popliteal fossa].

A 12-year-old boy was referred by the general practitioner with a 3-week history of pain in the popliteal fossa. There was no sign of trauma or infection, physical examination was normal, and his CRP level was mildly elevated. X-ray and MRI revealed a Brodie's abscess, which was treated surgically and with antibiotics and he made a good recovery.