Published online Dec 28, 2011. doi: 10.4329/wjr.v3.i12.298
Revised: May 1, 2011
Accepted: July 4, 2011
Published online: December 28, 2011
AIM: To compare the difference between tumor-induced lymph node enlargement and inflammation-induced lymph node enlargement by contrast-enhanced ultrasonography and pathological findings.
METHODS: A model of tumor-induced lymph node metastasis was prepared by embedding a VX2 tumor into the hind paws of white rabbits. A model of inflammation-induced enlargement was prepared by injecting a suspension of Escherichia coli into separate hind paws of white rabbits. Then, a solution of Sonazoid™ (GE Healthcare, Oslo, Norway) was injected subcutaneously in the proximity of the lesion followed by contrast-enhanced ultrasonography of the enlarged popliteal lymph nodes.
RESULTS: In the contrast-enhanced ultrasonography of the tumor-induced metastasis model, the sentinel lymph node was imaged. An area of filling defect was observed in that enlarged lymph node. In the histology examination, the area of filling defect corresponded to the metastatic lesion of the tumor. Contrast-enhanced ultrasonography of the model on inflammation-induced lymph node enlargement, and that of the acute inflammation model performed 3-7 d later, revealed dense staining that was comparatively uniform. The pathological findings showed acute lymphadenitis mainly due to infiltration of inflammatory cells. Contrast-enhanced ultrasonography that was performed 28 d post-infection in the acute inflammation model showed speckled staining. Inflammation-induced cell infiltration and fiberization, which are findings of chronic lymphadenitis, were seen in the pathological findings.
CONCLUSION: Sentinel lymph node imaging was made possible by subcutaneous injection of Sonazoid™. Contrast-enhanced ultrasonography was suggested to be useful in differentiating tumor-induced enlargement and inflammation-induced enlargement of lymph nodes.