Extrarenal manifestations of severe acute pyelonephritis: CT findings in 21 cases

The aim of this study is to report the extrarenal computerized tomography (CT) findings in patients with acute pyelonephritis (APN). Twenty-one CT examinations of 20 patients [19 women and one man, with ages ranging from 18 to 57 years (mean -35.2 years)], presenting either with a clinical diagnosis of APN (n=17) or with a suspected acute appendicitis, fever of unknown origin, and adult respiratory distress syndrome, one in each, were retrospectively reviewed. None had a known preexisting systemic disease. Results showed that renal abnormalities were seen on CT in all patients. In addition, ascites was detected in all women patients associated with subcutaneous edema in five of them. A thickened gallbladder wall was found in 19 cases, all were women, and periportal tracking and a dilated inferior vena cava in 17 CTs. Pleural effusion and thickened interlobular septa were present in 16 and 15 studies, respectively. Relevant laboratory findings included hypoalbuminemia in 14, elevated liver enzymes in 11, hypocholesterolemia in nine, and elevated LDH levels in six cases. In conclusion, radiologists should be familiar with the extrarenal imaging features of APN that may be seen on CT, and on ultrasonography as well, and should look for renal abnormalities to diagnose a clinically unsuspected APN. Alternatively, APN should be included in the differential diagnosis of systemic diseases that cause gallbladder wall thickening to avoid misdiagnosing it as acute cholecystitis.