THE CISTERNA CHYLI - A POTENTIAL MIMIC OF RETROCRURAL LYMPHADENOPATHYON CT SCANS

PURPOSE: To determine the normal appearance of the cisterna chyli and how it may mimic an enlarged retrocrural lymph node on computed tomogr aphic (CT) images. MATERIALS AND METHODS: CT scans were reviewed in 18 patients (17 with cancer, one with benign disease) who had tubular re trocrural structures of attenuation near that of water. The location, diameter, length, CT attenuation, duration of finding, change in size, and the status of intercurrent malignancy were recorded. RESULTS: The cisterna chyli was variably located at T12-L1 (n = 11), at T11-T12 (n = 5), and at T-12 (n = 2). The average length was 3 cm. The average C T attenuation was 12.5 HU. On serial scans in 14 patients, the average change in size was 2.2 mm despite progression or regression of malign ant disease at other sites in 11 patients. CONCLUSION: The cisterna ch yli can mimic the appearance of an enlarged retrocrural lymph node. Pr oper identification depends on its characteristic location, tubular co nfiguration, attenuation closer to that of water than soft tissue, and lack of substantial change in size despite changes in disease at othe r sites.