Acute lymphoblastic leukaemia (ALL) is the most common kind of childhood malignancy. Although the vast majority of patients are presented with medullary signs and symptoms such as an abnormal blood count, about one third will initially be presented with musculo-skeletal complaints (with or without radiological abnormalities) as the only apparent abnormality. These skeletal manifestations in ALL are not pathognomonic and may mimic several orthopaedic conditions, such as juvenile rheumatoid arthritis, osteomyelitis, septic arthritis and transient synovitis. This may therefore contribute to a delay in diagnosis, resulting in higher morbidity and mortality rates. However, musculoskeletal manifestations in leukaemia are usually associated with a precursor-B-ALL and have a good prognosis.

The purpose of this review is to highlight the diagnostic pitfalls in this type of ALL. ALL should always be considered as a differential diagnosis in any child with unexplained or persistent bone pain and a bone marrow examination is highly recommended when steroid therapy is being considered.

(BELG J HEMATOL 2012;3:3–11)