Ventriculoperitoneal shunt is the most common treatment to manage hydrocephalus; it is unfortunately burdened by up to 25% of complications. The peritoneal approach may expose patients to many complications, however the formation of a liver pseudocyst is a rare occurrence, and its mechanisms are still largely unknown.

We report the case of a 69-year-old woman with ventriculoperitoneal shunt, inserted for the management of post aneurysmal subarachnoid hemorrhage hydrocephalus, presenting to the Accident and Emergency for acute cholecystitis. Besides confirming the diagnosis, an ultrasound investigation revealed the presence of a hepatic cyst. Conservative treatment with antibiotics and non-steroidal anti-inflammatory drugs was performed with favorable outcome and resorption of the cyst. Interestingly the patient kept on presenting several similar episodes managed well by non-steroidal anti-inflammatory drugs alone, each of them associated with transient symptoms and signs of ventriculoperitoneal shunt malfunction. Computerized Tomography brain and lumbar puncture were normal, whereas CT abdomen showed the ventriculoperitoneal shunt distal catheter passing through the hepatic cyst. Given the ventriculoperitoneal shunt malfunction, in the context of an infective/inflammatory process a conversion of the ventriculoperitoneal shunt into a ventriculo-atrial shunt was carried out with successful clinical outcome.

Based on current literature we propose a clinical and radiological classification of such pseudocysts related to ventriculoperitoneal shunt. Clinical presentation, diagnostic findings and management options are proposed for each type: purely infective, spurious (infective/inflammatory) and purely inflammatory. In the absence of system infection, a simple replacement of the distal catheter seems to be the best solution.