We report a 4-year-old boy who presented with multiple pruritic, annular, erythematous plaques on the lower extremities of 1 week's duration. Histopathology of an affected area revealed a dense dermal infiltrate of eosinophils and flame figures without evidence of vasculitis. A diagnosis of eosinophilic cellulitis (EC), or Wells syndrome, was made. The patient had an excellent response to topical and systemic steroids following 1 week of treatment. This case appeared to be idiopathic, as there was no cause identified such as arthropod bites or tinea infection. The patient's EC cleared and has not had a recurrence.

Differentiation of osteomyelitis from cellulitis or septic arthritis can be difficult. The radiological examination often does not have the characteristic features. Seventy of 71 children with osteomyelitis had focal areas of increased radioactivity at the site of the infection. The addition of "blood pool" images aids in the interpretation of the study as they permit evaluation of the effect of hyperemia. The 13 childrenwith cellulitis had diffuse increase in radioactivity involving both the bones and soft tissues. Bone imaging as the initial screening procedure for osteomyelitis is recommended.

Fifty patients with cellulitis were evaluated prospectively using cultures of aspirates from the advancing edge of cellulitis, skin biopsy specimens, and blood. Potential microbial pathogens were isolated in 13 patients. Biopsy specimen cultures were positive in ten patients, while aspirate and blood cultures were positive in five and two, respectively. Aspirate, biopsy, or blood cultures were more often positive in patients with apparent primary lesions than in patients without such lesions. Apparent primary sites of infection were identified and cultured in 24 patients. beta-Hemolytic streptococci were isolated from 17 primary lesions, and coagulase-positive staphylococci were present in 13. Both organisms were isolated from ten primary lesions. Among patients with positive aspirate, biopsy, and/or blood cultures, the same pathogens were also isolated from primary sites in ten of ten patients. Clinical features, including temperature, white blood cell count, and erythrocyte sedimentation rate, were not predictive of positive aspirate, biopsy, or blood cultures. These cultures provided no microbiologic information that was not obtainable from culture of primary lesions.

Sequential studies with 99mTc-methylene diphosphonate (99mTc-MDP) and 67Ga were performed in 40 patients to determine the role of each agent in evaluating osteomyelitis, cellulitis, and spetic arthritis. Apart from the value of 67Ga in distinguishing cellulitis from osteomyelitis, it is a good adjuvant to 99mTc-MDP imaging in chronic osteomyelitis to identify continuing or recurrent sepsis and localize the focus of infection more precisely.

The 99mTc-phosphate bone scan has become a sensitive, reliable, and safe method for evaluating the patient with suspected inflammatory disease of bone. The scan may become positive as early as the first 24 hr after the symptoms and 10-14 days before roentgenographic changes occur. It can be used to differentiate successfully a variety of diseases from osteomyelitis, and in conjunction with 67Ga-citrate scan has become a mainstay in the work-up of the patient with infectious disease. Applications of the bone scan to infectious diseases in pediatric practice are especially helpful, since these diseases are common problems in this age group. Increased experience with the 99mTc-phosphate bone scan has already defined several areas of "limitations" in evaluating inflammatory disease."Cold" defects, negative scans in early stages of osteomyelitis, and "extended uptake" may all pose problems in interpretation, but careful correlation of the bone scan results with clinical history and physical findings, blood cultures, and roentgenography will significantly reduce these problems.

Magnetic resonance (MR) imaging was performed in 17 patients, 11-84 years of age, referred for evaluation of possible osteomyelitis involving the appendicular skeleton. MR imaging permitted successful identification of osteomyelitis in ten patients (four acute, two subacute with Brodie abscess, two chronic, and two acute with septic arthritis) and of cellulitis in the absence of osteomyelitis in four patients, including one with a soft-tissue abscess. Active osteomyelitis was excluded in three patients. Both T1- and T2-weighted spin-echo sequences were needed to evaluate osteomyelitis. T2-weighted images were needed to identify foci of active infection. MR images provided more accurate and detailed information regarding the extent of involvement than did radionuclide bone scans, computed tomographic scans, or standard radiographs. It permitted the differentiation of septic arthritis or cellulitis from osteomyelitis. In this limited series, MR imaging was particularly useful for seeking foci of active infection in areas of chronic osteomyelitis complicated by surgical intervention or fracture.

Sixty-five children were evaluated for presence of skeletal inflammatory and ischemic disease with bone scans and roentgenograms. Several characteristic scintigraphic patterns were observed. Bone scans were significantly more sensitive than roentgenograms in early diagnosis of osteomyelitis and its differentiation from cellulitis, septic arthritis, and bone infarction. The child presenting with possible inflammatory bone disease now is benefited by this important refinement in diagnosis. Faced with the difficult dilemma of choosing appropriate therapy in these frustratingly similar problems, the physician can integrate the clinical findings with nuclear imaging to arrive at early appropriate diagnosis and management.

OBJECTIVE: This study was performed to evaluate the diagnostic value of MR imaging in differentiating necrotizing fasciitis from cellulitis. MATERIALS AND METHODS: Spin-echo T1-weighted, T2-weighted, and contrast-enhanced T1-weighted spin-echo sequences were performed in 15 patients with clinically suspected necrotizing fasciitis. In two other patients, only unenhanced imaging was performed. The MR imaging results were correlated with the surgical findings in 11 cases, with autopsy in one case, and with the clinical outcome in five cases. RESULTS: Cellulitis was diagnosed when subcutaneous thickening with fluid collections was revealed on T2-weighted images and when subcutaneous tissue or superficial fascia or both showed contrast enhancement. For the diagnosis of necrotizing fasciitis, imaging revealed additional involvement of deep fasciae with fluid collections, thickening, and enhancement after contrast administration. According to these criteria, we found 11 cases of necrotizing fasciitis and six of cellulitis. MR imaging identified all 11 cases of necrotizing fasciitis correctly when compared with the surgical findings. One false-positive case of cellulitis was overstaged and was thought to be necrotizing fasciitis. Contrast-enhanced T1-weighted sequences delineated abscesses and areas of necrosis more clearly than T2-weighted sequences did, but showed no additional lesions. CONCLUSION: When no deep fascial involvement is revealed with MR imaging, necrotizing fasciitis can be excluded. However, because its sensitivity exceeds its specificity, MR imaging tends to overestimate the extent of deep fascial involvement. Therefore, the therapeutic regimen should be based on a combination of clinical findings and MR imaging.

The purpose of this study was to assess whether gadolinium-enhanced magnetic resonance imaging (MRI) provides diagnostic information beyond that given by nonenhanced imaging in the evaluation of musculoskeletal infectious processes and whether it can be used for differentiating infectious from noninfectious inflammatory lesions. Magnetic resonance images performed with and without intravenous gadolinium-DTPA in 34 cases in which musculoskeletal infection had been clinically suspected were reviewed. Infectious lesions--including osteomyelitis, pyarthrosis, abscess, and cellulitis--were confirmed in a total of 22 cases: in 15 by biopsy or drainage and in 7 by clinical course. Our results show that gadolinium-DTPA-enhanced MRI is a highly sensitive technique in diagnosing musculoskeletal infectious lesions. It is especially useful in distinguishing abscesses from surrounding cellulitis/myositis. Lack of contrast enhancement rules out infection with a high degree of certainty. However, contrast enhancement cannot be used to reliably distinguish infectious from noninfectious inflammatory conditions.