Diagnostic criteria in renal and hepatic cyst infection

Cyst infection is a severe complication of renal and hepatic cystic disease that frequently leads to hospitalization. In most cases the diagnosis of cyst infection is made empirically as a cyst aspirate is frequently unavailable. This study aims to evaluate diagnostic criteria, microbiological findings and imaging modalities needed to diagnose cyst infection. In order to do so, we evaluated reports that characterize cyst infection cases published in the English language between 1948 and January 2014. We identified 70 articles documenting a total of 215 cyst infection cases (renal n = 119; hepatic n = 96). Six studies, including 74 cases of renal and 61 cases of hepatic cyst infection, used diagnostic criteria. The criteria that led to a definite cyst infection diagnosis were consistent, whereas criteria for a 'probable diagnosis' varied considerably. Cyst infection cases commonly have abdominal pain, fever and elevated serum inflammatory markers. Urine and blood cultures frequently remained negative, even in definite cases. The diagnostic properties of (18)fluorodeoxyglucose positron-emission computed tomography ((18)F-FDG PET/CT) are probably best to diagnose cyst infection. Cyst aspirate indicating infection is currently the gold standard in diagnosing cyst infection. If not available, a combination of clinical and biochemical parameters is necessary to make a well-considered diagnosis, preferably including (18)F-FDG PET/CT.