Evaluation of Mesenteric Lymph Nodes in a Pediatric Population with Mesenteric Lymphadenitis Using Superb Microvascular Imaging.

BACKGROUND This study aimed to evaluate superb microvascular imaging (SMI) as an adjunctive imaging method to evaluate mesenteric lymph nodes in children with mesenteric lymphadenitis compared with healthy children. MATERIAL AND METHODS A retrospective study compared children with mesenteric lymphadenitis (n=27) and healthy children (n=30). Lymph node size was determined using grayscale ultrasonography and parameters of lymph node vascularity were compared using color Doppler flow imaging (CDFI) and SMI. The diagnostic performance of ultrasound (US), US combined with SMI, and US combined with CDFI were compared. RESULTS Lymph nodes from children with mesenteric lymphadenitis (n=77) and normal lymph nodes (n=84) were evaluated by SMI, which showed that the least diameter of lymph nodes in cases of mesenteric lymphadenitis was 0.58±0.15 mm and of normal mesenteric lymph nodes was 0.47±0.08 mm (p<0.001). SMI identified 92.6% of abnormal mesenteric lymph nodes while CDFI detected 85.2%. US combined with SMI had the highest sensitivity (81.5%), and specificity (78.9%) compared with US alone (sensitivity, 63.0%; specificity, 64.9%), and compared with US combined with CDFI (sensitivity, 74.1%; specificity, 75.4%). US combined with SMI and US combined with CDFI achieved the same specificity (76.7%), which was higher than that of US alone (66.7%). CONCLUSIONS SMI was superior to color Doppler flow imaging in evaluating the microvasculature in lymphadenopathy in mesenteric lymphadenitis. SMI may be used as an adjunct to grayscale ultrasonography to assist in identifying mesenteric lymphadenopathy in pediatric patients.

Inflammatory consequences of the translocation of bacteria and endotoxin to mesenteric lymph nodes.

BACKGROUND: Translocation of intestinal bacteria to mesenteric lymph nodes (MLNs) has been documented in humans under a variety of circumstances, yet its clinical significance remains to be established. The aim of this study was to correlate detectable translocation to MLNs of bacteria and endotoxin with local and systemic signs of inflammation. METHODS: From each of 10 patients with carcinoma of the cecal region two MLNs were harvested prior to resection. The presence of bacteria and endotoxin in the lymphatic tissue and blood was determined by culture methods and DNA preparation (PCR) and by a Limulus assay, respectively. Inflammatory mediators were determined in plasma and in MLN homogenates. RESULTS: Viable bacteria were detected in MLNs of 7 patients and in 9 of 20 lymph nodes. PCR revealed traces of bacteria in 4 patients and in 6 of their MLNs. Combining both modalities, the translocation rate was 80% and 55% for patients and MLNs, respectively. There was no detectable bacteremia. Endotoxin was found in the plasma of 7 patients and in 9 MLNs from 5 patients. There was no correlation between culture findings and endotoxin concentrations. Moreover, bacteriological data did not correspond to local or systemic inflammation. The group of MLN with detectable endotoxin differed significantly from LPS-negative nodes with respect to interleukin-6, interleukin-10, and sCD14. Systemic concentrations of endotoxin and inflammatory parameters did not correspond to levels within MLNs. CONCLUSION: Translocation to MLNs occurs in patients with cecal carcinoma. This, however, seems not to be of major clinical significance if no additional physiologic insults are encountered. Irrespective of the presence of bacteria, there are variations in inflammatory reactions between lymph nodes from one and the same patient, probably reflecting fluctuating response mechanisms to low-grade translocation.

Effects of somatostatin analogues and vitamin C on bacterial translocation in an experimental intestinal obstruction model of rats.

The passage of viable endogenous bacteria and their products across the intact intestinal mucosal barrier, disseminating to the mesenteric lymph nodes, peritoneal cavity, spleen, liver, and circulation, is defined as bacterial translocation. Intestinal obstruction induces bacterial translocation due to mucosal disruption, motility dysfunction, and increased intestinal volume, leading to bacterial overgrowth. In a rat model of intestinal obstruction, the effects of both high-dose vitamin C (350 microg/kg), an antioxidant agent known to have a cytoprotective effect in ischemia-reperfusion injury, and somatostatin (20 microg/kg), a gastrointestinal antisecretory agent, in preventing bacterial translocation were studied. Both intestinal and liver samples from the rats was observed, and it was found that the rate of bacterial translocation was 100% in the control group, and only 43% for the rats who were given intraperitoneal vitamin C and somatostatin. The difference was statistically significant. In conclusion, we are convinced that vitamin C and somatostatin analogues may have protective effects against bacterial translocation in mechanical bowel obstruction.

Fibrinogen/fibrin deposits in mesenteric lymphadenitis due to Yersinia pseudotuberculosis type I: morphologic, immunohistochemical and electron microscopic studies of one case.

A case of mesenteric lymphadenitis due to Yersinia pseudotuberculosis type I is described in a young adult. The diagnosis is suggested by histological appearance and confirmed by serological tests. Histological and semithin sections reveal granulomas with central microabscesses and concentric coagulative necrosis. By histochemical and immunohistochemical techniques, fibrinogen/fibrin deposits are observed as a prominent intercellular meshwork around microabscesses or as loosely intertwining strands in small granulomas. Electron microscopy shows fibrinogen/fibrin deposits closely associated both fibrous long-spacing (FLS) fibers and thin collagen fibers. The pathogenesis and type of granuloma as well as the significance of fibrinogen/fibrin deposits are discussed with reference to current literature.