We would like to present a rare case of a giant abdominal CSF pseudocyst occurring as a complication of ventriculoperitoneal shunt (VP shunt) surgery.
A four-year old female child presented with a history of abdominal distension, lethargy and fever of one-week duration. The child had undergone lumbar meningomyelocele excision and VP shunt surgery at four months of age. Clinical examination revealed a distended non tender abdomen. There was no suggestion of bowel obstruction or ascites. There was no neurological deficit. Abdominal sonogram revealed a large intra-abdominal fluid collection with internal echoes. To assess the exact size and the nature of the lesion a CT scan was done. The CT revealed a large loculated cyst measuring 13x12 x 5 cms in its largest dimensions and occupying mainly the lower abdomen and pelvis. The large and the small bowel were displaced around the cyst. The tip of the VP shunt tube was seen within the cyst [Figure - 1] . In addition, CT revealed a low-lying cord with syringohydromyelia [Figure - 2] . A diagnosis of CSF pseudocyst was made. The pseudocyst was drained percutaneously and the shunt tube was removed. The pseudocyst fluid revealed inflammatory cells and the culture yielded no bacterial growth.
The use of peritoneal cavity for CSF absorption in VP shunting was introduced in 1905 by Kausch  . In 1954, Harsh first described a periumbilical pseudocyst  . Since then, 130 cases of CSF pseudocyst in children have been reported in literature  . Abdominal CSF pseudocyst is a rare but important complication of VP shunting. Other complications include intestinal obstruction, urinary bladder perforation and shunt migration. The etiology remains poorly understood. Chronic inflammation  , multiple shunt revisions  , increased CSF protein content, peritoneal adhesions, malabsorption of CSF secondary to subclinical peritonitis are a few proposed mechanisms.
The most frequent symptoms of an abdominal pseudocyst are pain and distension in the abdomen followed by symptoms of elevated intracranial pressure. Fever and lethargy are also infrequently seen as presenting symptoms  .
The diagnosis of pseudocysts can be done readily by a sonographic examination  supplemented with abdominal radiographs to know the position of the tip of the shunt tube, A CT scan would confirm the findings and in addition can define the exact nature and size of the pseudocyst. The differential diagnosis includes cysts of the mesentery and omentum, small bowel duplication cysts, abdominal abscesses, loculated fluid in the peritoneal cavity and free peritoneal fluid  .
Treatment involves surgical removal of the catheter with or without excision of the pseudocyst and placement of a new catheter intraperitoneally in a different quadrant or an intraatrial shunt  . Recurrences are rare especially if appropriate medical treatment of a infection is instituted  .
Rainov N, Schobess A, Heidecke V, Burkert W. Abdominal CSF pseudocysts in patients with ventriculoperitoneal shunts. Report of fourteen cases and review of literature. Acta Neurochir (Wien) (1994) 127: 73-78.