ID #134 Extra-peritoneal abdominal wall pseudocyst due to migration of distal Ventriculo-Peritoneal shunt catheter in a patient with CNS Germinoma and Hypothalamic Obesity.
Magimairajan Issai Vanan, Colin Kazina, Hayley Moffat, Meziane Brizini, Hadeel Hassan, Tina DrimesAbstract
Background
Ventriculoperitoneal (VP) shunt complications such as infection and intraperitoneal pseudocyst formation are well recognized. Pseudocysts arising in the subcutaneous extraperitoneal abdominal wall are exceptionally rare. We describe a case associated with hypothalamic obesity and distal catheter migration.
Methods
Clinical presentation, imaging, treatment course, and follow-up findings of a single pediatric patient with CNS germinoma and VP shunt placement were reviewed.
Results
A 12-year-old female presented with one month of blurry vision, polyuria, and polydipsia. She was diagnosed with diabetes insipidus and pan-hypopituitarism. MRI revealed bifocal pineal and suprasellar lesions (2.8 × 4.9 × 2.4 cm) causing obstructive hydrocephalus. Serum and CSF germ cell tumor markers were negative; biopsy confirmed germinoma. A VP shunt was placed, and therapy started per COG-ACNS1123 Stratum 2. During the third month of therapy, she developed central hypothalamic obesity managed with diet and exercise. At four years of follow-up, she presented with abdominal pain; CT imaging demonstrated migration of the distal VP shunt catheter into the abdominal wall with lobulated subcutaneous fluid collections surrounding the tip. Her pain resolved with analgesics, and she was managed expectantly. MRI of abdomen at 5 1/2 years revealed a persistent pseudocyst measuring 28 (L) × 8.3 (T) × 4.6 (AP) cm, and she remained asymptomatic. Her CNS GCT remains in remission with no new neurological symptoms. All previously reported cases of abdominal wall pseudocyst are associated with severe obesity. In our patient, hypothalamic obesity (BMI 36.61) and increased intra-abdominal pressure likely contributed to catheter migration into the abdominal wall dead space.
Conclusion
Abdominal wall pseudocysts due to distal VP shunt migration are rare but may occur in patients with obesity or increased intra-abdominal pressure. Prevention may be optimized by placing the distal catheter beneath the abdominal fat pad, adjacent to the rectus abdominis muscle, and ensuring secure peritoneal closure.