Malignant Peritoneal Mesothelioma in the setting of a Ventriculo-Peritoneal Shunt: A novel clinical presentation

Malignant Peritoneal Mesothelioma Arising in Young Adults With Long-standing Indwelling Intra-abdominal Shunt Catheters

Only 50% to 70% of patients with mesothelioma report asbestos exposure. Other exposures (eg, radiation) play a role in some cases, but some patients have no obvious cause. We describe a series of patients with long-standing indwelling intra-abdominal shunt catheters who developed malignant peritoneal mesothelioma, suggesting a novel association. We identified 7 patients who had shunts and subsequently developed mesothelioma (5 women; median age: 31 y, range: 18 to 45 y). Clinical history and pathology materials were reviewed, and RNA sequencing was performed. Clinical presentations varied; 6 patients had hydrocephalus and a ventriculoperitoneal shunt, and 1 patient had portal hypertension and a portoatrial shunt. The median duration of shunt therapy in 5 cases was 29 years (range: 12 to 35 y); the remaining 2 patients also had shunts for many years, but specific details were unavailable. Two patients had radiotherapy for malignancies in childhood. One had an alleged exposure to asbestos and 1 had prior exposure to talc. The rest had no known risk factors. Histologically, all tumors were purely epithelioid. Treatments included surgical debulking, chemotherapy, and palliative care. All 7 died of disease (median survival: 7 mo, range: 1 to 18 mo). Molecular testing showed loss of NF2 and CDKN2A/B and a BAP1 mutation in 1 case, and no genomic alterations associated with mesothelioma in 2 cases. Peritoneal mesothelioma may represent a complication of long-standing indwelling shunt catheters. The mechanism is unknown, but chronic peritoneal irritation may play a role. Albeit rare, mesothelioma should be considered in patients with a shunt who present with new ascites.

Inflammation and obstruction of distal catheter slits in ventriculoperitoneal shunts: likely role of graphite

OBJECTIVE

Tissue reactions that contribute to obstruction of peritoneal catheters in ventriculoperitoneal shunt systems are not well characterized. Several recent rapid obstructions in children prompted a retrospective quality assurance review.

METHODS

The authors conducted a detailed investigation of 22 surgically explanted peritoneal shunt catheters and 8 autopsy cases with documented distal shunt obstruction. Patients' medical histories were reviewed, and the catheters and/or tissues were subjected to conventional histological and immunohistochemical evaluations. In addition, 3 cases were subjected to electron microscopic examination including elemental analysis.

RESULTS

The majority of symptomatic obstructions were associated with distal slit catheters (17 slit, 3 open-end, and 2 unknown type). Among the autopsy cases, deaths were attributed to shunt failure in 2 cases of slit catheter obstruction, 1 case of open-end catheter obstruction, and 1 case of catheter withdrawal from the peritoneal cavity. The early tissue response consisted of a predominantly T lymphocyte accumulation with phagocytosis of graphite particles by macrophages. This is associated with proliferation of fibroblasts, mesothelial cells, and blood vessels, which can grow through the slits and occlude the catheter lumen. As the inflammation subsides after approximately 1 year, the tissue plug becomes collagenized and calcified.

CONCLUSIONS

This study, supported by experimental literature in other organ systems, indicates that graphite used to coat the slit openings of distal catheters from ventriculoperitoneal shunts likely predisposes to obstruction. Neurosurgeons and manufacturers should consider the potential negative consequences of this shunt design. The authors concur with previous recommendations that slit-valve distal catheters should not be used for ventriculoperitoneal shunting unless they can be proven safe and efficacious in a controlled trial.