Reports of the upper limits of normal for lymph node size at abdominal computed tomography have varied from 6 to 20 mm. Establishment of an upper limit for node size by specific location, analogous to that which has been reported for mediastinal lymph nodes, was sought. Short-axis diameters of the lymph nodes were measured in 130 patients who were not likely to have enlarged abdominal lymph nodes. Seven locations were defined, and the largest nodal measurement for each was recorded. Histographic analysis and nonparametric statistical methods were used to determine threshold values for the maximum node size in each region. The upper limits of normal by location were as follows: retrocrural space, 6 mm; paracardiac, 8 mm; gastrohepatic ligament, 8 mm; upper paraaortic region, 9 mm; portacaval space, 10 mm; porta hepatis, 7 mm; and lower paraaortic region, 11 mm. Lower paraaortic lymph nodes larger than 11 mm by short-axis measurement are abnormal. In other locations, nodes smaller than 1 cm may be abnormal if the determined thresholds are exceeded.

Adult polycystic kidney disease (APKD) is associated with cyst formation in the kidney, liver, pancreas, esophagus, ovary, uterus, and brain. Four patients with APKD (aged 45-65 years) with computed tomographic evidence of seminal vesicle cysts are described. All seminal vesicles contained cystic masses with attenuation values of 0-30 HU. Seminal vesicle thickness was 3-4 cm (normal, 1.5 cm). High-attenuation walls separated the cysts, which were 3-35 mm in diameter. All patients had typical renal stigmata of APKD. None had cysts elsewhere, except one patient with hepatic cysts. Postmortem examination in one patient confirmed the seminal vesicle cysts as well as APKD. It is likely that a basement membrane defect allows cyst formation in multiple organs, presumably including the seminal vesicles. Because of the association of seminal vesicle cysts with ipsilateral urogenital anomalies, and because only 60% of patients with APKD have a relevant familial history, the kidneys of patients with cross-sectional imaging evidence of seminal vesicle cysts should also be studied.