A 14-year-old boy was referred to the orthopaedic clinic by his general practitioner, reporting of a 6-week history of left thigh pain. Clinical examination was unremarkable. Radiographs demonstrated a periosteal reaction at the proximal femur. MRI scans demonstrated a stress fracture of the femur, with no associated sinister features and no evidence of a pathological lesion. As the fracture healed and symptoms improved, the patient became unwell with weight loss, lethargy, chest and jaw pain and fevers. After multiple blood tests over a 25-day period, including five full blood counts and two normal blood films, a third blood film finally demonstrated blasts in keeping with acute leukaemia. We discuss a literature review of musculoskeletal manifestations of leukaemia and the often atypical presentations found.