REVIEW HEMATOLOGY

Musculoskeletal manifestations in children with acute lymphoblastic leukaemia

Summary

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)

Pseudohyperkalaemia in T-ALL: how to avoid life-threatening hypokalaemia

Summary

Tumour lysis syndrome is a well-known life-threatening complication in children with acute leukaemia and hyperleukocytosis. It is characterised by hyperkalaemia but it should be distinguished from pseudohyperkalaemia. Various underlying factors for this phenomenon of pseudohyperkalaemia have been suggested. Here, we describe two children with T-cell acute lymphoblastic leukaemia who presented with hyperleukocytosis and hyperkalaemia, in whom the diagnosis of pseudohyperkalaemia was made. We demonstrate that in extreme leukocytosis the use of a vacuum system, pneumatic transport, and sample centrifugation contribute all together to pseudohyperkalaemia. As the leukocyte count decreases, plasma potassium levels are more reliable. Based on our results we suggest to measure potassium in a whole blood sample immediately brought to the laboratory for minimising false results due to ex vivo cell lysis.

(BELG J HEMATOL 2012;3:12–6)