Teaching NeuroImages: massive abdominal CSFoma.

A 31-year-old woman with congenital hydrocephalus status post ventriculoperitoneal shunt placement 23 years earlier presented with abdominal distention. The patient denied fever, headache, or sensory or motor abnormalities. Examination was notable for a tense abdomen. CT of the abdomen and pelvis demonstrated a massive, loculated, CSFoma, or CSF pseudocyst (figure). Ventriculoperitoneal shunts are associated with a variety of complications including disruption of the tube, obstruction of the tip, infection, intestinal perforation, tip migration, and CSFoma development. CSFoma is a rare complication, thought to be caused by low-grade shunt infection, chronic inflammation, increased CSF protein, or peritoneal adhesions, and is estimated to occur in 1.0% to 4.5% of cases, with a typical occurrence within 3 weeks to 5 years of shunt placement. Treatment consists of external drainage or surgical excision followed by reconstruction of the shunt system.