Dilemma in Differentiating between Acute Osteomyelitis and Bone Infarction in Children with Sickle Cell Disease: The Role of Ultrasound

Abstract

BackgroundDistinguishing between acute presentations of osteomyelitis (OM) and vaso-occlusive crisis (VOC) bone infarction in children with sickle cell disease (SCD) remains challenging for clinicians, particularly in culture-negative cases. We examined the combined role of ultrasound scan (USS), C - reactive protein and White blood counts (WCC) in aiding early diagnosis in children with SCD presenting acutely with non-specific symptoms such as bone pain, fever or swelling which are common in acute osteomyelitis or VOC.MethodsWe reviewed the records of all children with SCD who were discharged from our department from October 2003 to December 2010 with a diagnosis of osteomyelitis based on clinical features and the results of radiological and laboratory investigations. A case control group with VOC who were investigated for OM were identified over the same period.ResultsIn the osteomyelitis group, USS finding of periosteal elevation and/or fluid collection was reported in 76% cases with the first scan (day 0–6). Overall 84% were diagnosed with USS (initial +repeat). 16% had negative USS. With VOC group, USS showed no evidence of fluid collection in 53/58 admissions (91%), none of the repeated USS showed any fluid collection. Mean C-reactive protein (CRP), and white cell count (WCC) were significantly higher in the OM.ConclusionThe use of Ultrasound in combination with CRP and WCC is a reliable, cost-effective diagnostic tool for differentiating osteomyelitis from VOC bone infarction in SCD. A repeat ultrasound and/or magnetic resonance imaging (MRI) scan may be is necessary to confirm the diagnosis.

Contribution of Reduced Interleukin-10 Levels to the Pathogenesis of Osteomyelitis in Children with Sickle Cell Disease

“…Osteomyelitis can present as an acute or chronic inflammatory destruction of the bone and is characterized by progressive destruction of infected bone and recruitment of osteocytes to the infection sites. These sites include femur, humerus, vertebra, ribs, and sternum (4,5), although any bone may be infected (3,5,6). Osteomyelitis is multifactorial in nature and is influenced by local factors relating to bone lesion and type of infectious microorganism (5,7), together with an inherited predisposition and immunological dysfunction (3,8,9).…”

“…Distinguishing the acute presentation of osteomyelitis from VOC relies on clinical assessment (fever and pain on admission, swelling of affected limb, and painful sites) and radiological findings (ultrasound scans, magnetic resonance imaging [MRI]), in combination with elevated C-reactive protein (CRP) and white blood cell (WBC) counts (5,10). Distinct cytokine profiles were reported during early (1 to 4 months) and late (5 to 12 months) osteomyelitis episodes; the early-episode profiles are highlighted by an increased frequency of high tumor necrosis factor alpha (TNF-␣) and interleukin-4 (IL-4) producers, while the late-episode profiles are exemplified by increased frequencies of IL-10, IL-6, and IL-2 producers (11).…”

Utility of unenhanced fat-suppressed T1-weighted MRI in children with sickle cell disease — can it differentiate bone infarcts from acute osteomyelitis?

“…Bone scans are of limited utility [5,8]. Some studies report high reliability of US for the differentiation of bone infarct versus osteomyelitis in children with SCD because of US findings of soft-tissue abnormalities and subperiosteal collection [6,12,13]. However in our US experience and based on the results of this MRI study, soft-tissue changes and subperiosteal fluid collection occur in both processes, so these cannot accurately distinguish between the two.…”

“…Both diagnoses also result in similar laboratory abnormalities including leukocytosis and elevated inflammatory markers (C-reactive protein and erythrocyte sedimentation rate) [4,6,7]. The gold standard for the diagnosis of osteomyelitis is a positive culture from a sampling of bone, synovial fluid or blood.…”

“…Lack of microbiological data does not exclude the diagnosis of osteomyelitis [4,7]. Thus most experts suggest the integration of clinical symptoms, laboratory findings and imaging studies for the differentiation of acute bone infarct and acute osteomyelitis in children with SCD [4,6,7]. It is important to realize that a bone infarct is 50 times more common than osteomyelitis in children with SCD [4,5].…”