Intracranial foreign material granulomas after cranial surgery.

Background: Various synthetic materials are used in neurosurgery and left in place intentionally during surgery for several purposes such as hemostasis, dural closure, or cranioplasty. Although leaving such substances in surgical sites is considered safe, in general, foreign body granuloma may occur months or years after intracranial surgery. Thus, far relatively little is known about treatment and outcome of such lesions.

Methods: A systematic review of 3466 histopathological examinations after cranial surgeries achieved over a 13-year period was performed. After excluding patients with Teflon granulomas or infection, a total of 12 patients with foreign body granulomas induced by synthetic material used in a prior surgery were identified. Patient records, imaging studies, and histopathological data were analyzed. Furthermore, postoperative outcome was assessed.

Results: Mean age at the second surgery was 51 years (range, 11-68 years). The median time between the primary and the secondary surgery was 13 months (range, 1-545 months). Eight patients (75%) presented with signs and symptoms related to the foreign body granulomas. Total resection of the foreign body granulomas was performed in all patients. The granulomas were induced by oxidized cellulose polymer (n = 6), suture material (n = 3), Gelfoam (n = 1), methylmethacrylate (n = 1), and bone wax (n = 1). The mean postoperative follow-up time was 54 months (range 1-137 months). There was symptomatic improvement in all instances. Imaging studies did not demonstrate any recurrence.

Conclusion: Despite its rarity, foreign body granuloma should be taken into consideration in the differential diagnosis of intracranial mass lesions especially in cases of suspected tumor recurrence after prior surgery. The pathogenesis of foreign body granuloma still needs further clarification. Our study demonstrates that they have good prognosis after surgical removal.