Teaching Case

A 13 year-old female patient had undergone surgery for acute appendicitis 5 weeks ago and than discharged. She referred to the hospital again 10 days after the surgery with swelling of right preauricular and submandibular regions, difficulty in swallowing, sore throat and fever of around 40 °C. On the physical examination of preauricular region, hyperemic and swollen appearance and tenderness were recognized. Petechiae are found on the palpebral conjunctiva, platal mucosa and extremities. Also an apical cardiac murmur was heard on the auscultation of the heart. Hematologic analysis showed anemia and increased white blood cell count (10700/ml.). The ESR was raised at 135mm/hr. 10 days later, left hip and bilateral knee pain, restricted and painful knee movements on the right knee and left hip and difficulty in walking developed.

A 13 year-old female patient had undergone surgery for acute appendicitis 5 weeks ago and than discharged. She referred to the hospital again 10 days after the surgery with swelling of right preauricular and submandibular regions, difficulty in swallowing, sore throat and fever of around 40 °C. On the physical examination of preauricular region, hyperemic and swollen appearance and tenderness are thought to be due to parotiditis and submandibular sialadenitis. Petechiae are found on the palpebral conjunctiva, platal mucosa and extremities. Also an apical cardiac murmur was heard on the auscultation of the heart. The other systems examinations were normal. Serological studies revealed no abnormality, but a hematologic analysis showed anemia and increased white blood cell count (10700/ml.). Laboratory tests revealed increased levels of CRP and LDH. The ESR was raised at 135mm/hr. Serum electrolytes levels showed decreased Na, K and Ca. Serum protein electrophoresis revealed increased amount of globulins, total proteins and decreased albumin and albumin/globulin ratio. Urine analysis of the patient showed microscopic hematuria and proteinuria. Two-Dimensional echocardiography demonstrated small vegetations on the mitral valve consistent with endocarditis. Than hemoculture of the patient was made and the organism grown was Staphylococcus aureus. Within the second hospitalization, 10 days later, left hip and bilateral knee pain, restricted and painful knee movements on the right knee and left hip and difficulty in walking developed. An MRI study of the upper abdomen,hips and thighs with 1.5 T MR scanner, in three planes with pre-post contrast SE T; FSE, PD and T2 W sequences were performed. Post contrast SE T1 WI and SE T2 WI were performed with fat saturation. MR images showed hepatosplenomegaly, left proximal and bilateral distal metaphyseal femoral osteomyelitis. Diagnosis of multifocal osteomyelitis was made both clinically and by MRI and also histologically by the specimens taken during left proximal hip and bilateral distal arthrotomies performed for the treatment.

Osteomyelitis is inflammation of bone and bone marrow usually caused by bacterial infections. Occasionally the disease may be caused by fungi, viruses or parasites. The most common infecting organisms of bone are Staphylococcus aureus, followed by Streptococcus, Pneumococcus, Haemophilus influenza, Escherichia coli and Pseudomonas aeruginosa. Female/male ratio is ¼.There are three major categories of pathogenesis of osteomyelitis. Hematogenous, direct inoculation (trauma, surgery) and extension from adjacent soft tissue disease. In children hematogenous osteomyelitis is the mostly seen type. Forty percent of osteomyelitis seen in this age group is multifocal. The infection begins in metaphyses where there is a rich blood supply and a slow flow in the venous side loops such that organisms can seed and proliferate in sinusoidal veins. In neonates, the intact vascular communications between the metaphysis and epiphysis result in epiphyseal involvement in up to 70 %, with potential for septic joint. Between the ages of 1 year and skeletal maturity, the cartilage provides a barrier to joint involvement also blood supply of the epiphysis and metaphysis is separate. Osteomyelitis should be suspected clinically on the basis of history, physical examination, the presence of risk factors and abnormal laboratory values. For certain diagnosis and identifying the causative agent taking blood, pus, joint fluid or bone samples are necessary. Imaging in children with suspected acute osteomyelitis is used to guide diagnosis and management. Plain radiographs are obtained to exclude other pathologic conditions such as tumor, fractures, or nonaccidental trauma. In early osteomyelitis, soft tissue swelling and loss of normal deep soft tissue planes are the only findings, with bone destruction not evident up to 15 days after the onset of symptoms. Sonography may be used to demonstrate joint effusions and subperiosteal fluid collections. Radionuclide scintigraphy ( Three phase skeletal scintigraphy, WBC-scan with In-111 or Tc 99m labeled leukocytes, Ga-67 scans ) is used to aid the diagnosis and determine multifocality of disease. Osteomyelitis appears as increased tracer uptake reflecting the hyperemia and initial bone resorption induced by the infectious process. Although three-phase bone scan has been shown to be sensitive in the detection of osteomyelitis in uncomplicated cases, specifity is poor, particularly in complicated cases. Specifity may be improved by adding Ga-67 scans or Indium -111 labeled WBC-scans. CT is of limited value in early osteomyelitis. It is useful in advanced disease to detect cortical destruction, periosteal reaction and bony sequestra. MRI is valuable in the diagnostic evaluation of acute and chronic osteomyelitis. MRI is prefered to CT for detecting osteomyelitis and soft tissue abscesses because it better depicts the marrow cavity and adjacent soft tissues. The primary MRI characteristics of osteomyelitis are those of marrow replacament by edema and infiltration by inflammatory cells, hemorrhage, fibrin and debris. The marrow changes have typically ill defined margins. T2 W sequences generally demonstrate an increase in signal intensity within the marrow. Decreased signal intensity is seen on T1 W sequences. STIR sequences also demonstrate increased signal of marrow. Following gadolinium , T1 W fat saturated sequence shows marrow enhancement. Infection may spread in both directions in the marrow cavity, penetrate the cortex, lift the periosteum, and rupture into adjacent soft tissues. If the bone under the elevated periost loses its blood supply, results in bone necrosis and sequestra formation. A thick sheath of new bone, or involucrum, may form around the devitalized bone by elevated periosteum, separated from the sequestra by granulation tissue. MRI can differentiate acute from chronic osteomyelitis. Chronic osteomyelitis demonstrates well-defined soft tissue abnormality, thickened cortex and a sharper interface between normal and diseased bone marrow. Early diagnosis of the disease is important for performing medical threatment ant preventing the disease to progress chronic stages which requires surgery such as sequestrectomy, irrigation of the cavity by placing a drain into it and than filling the cavity with healthy bone or muscle.