[Psoas abscess mimicking septic arthritis of the hip]

Primary psoas abscess is a relatively rare and imposes diagnostic and therapeutic challenges. We describe a 16-year-old boy who presented with fever, limp and the clinical picture of septic arthritis of the hip joint. He did not respond to conventional medical treatment. When the diagnosis of psoas abscess was made and the abscess was drained, he gradually recovered. The diagnosis of psoas abscess is frequently missed. Correct diagnosis is very important because usually, cure only follows surgical drainage.