Intracranial Foreign Body Granuloma Mimicking Brain Tumor Recurrence: A Case Series

Abstract

Background: Intracranial foreign body granuloma (FBG) is a rare inflammatory reaction to retained foreign material, manifesting acutely or months to years following neurosurgical procedures. Radiographically, FBG can mimic tumor progression, and tissue biopsy may be required to guide management.

Materials and methods: In this retrospective case series, we present unique clinico-radiographic and histopathological features of six neuro-oncological patients diagnosed with FBG between 2007 and 2019.

Results: All six patients (4 women and 2 men, aged 29-54 [median, 30.5] years) had undergone surgical resection of a low- (n = 4) or high-grade (n = 2) glioma. FBG manifestation postsurgery ranged from 1 day to 4 years and was predominantly asymptomatic (n = 5/6). Magnetic resonance imaging universally demonstrated one or multiple peripherally enhancing lesion(s) adjacent to the resection cavity. Histopathology in all (n = 4/4) resected specimens demonstrated an inflammatory reaction to foreign material, confirming FBG.

Conclusion: Intracranial FBG constitutes a rare but challenging treatment-related condition effectively managed by surgery, with important therapeutic implications in neuro-oncology.

Figure 1

Magnetic resonance imaging (MRI) characteristics and histopathological findings identified in patients with intracranial foreign body granuloma. (A): Patient 3. Axial IR‐FSPGR‐BRAVO postcontrast MRI, taken 3 months postsurgery, demonstrates nodular, contrast‐enhancing lesions in the left anterior temporal lobe (left panel), left insula (middle panel), and left corona radiata (right panel). Surgical resection of left temporal lesion confirmed foreign body granuloma. (B): Patient 5. Axial MRI, taken 4 years postsurgery, demonstrates a suspicious lesion located adjacent to the resection cavity in the right frontal lobe, characterized by peripheral enhancement on T1 postcontrast sequences and central diffusion restriction on DWI. Neuropathological evaluation of the resected lesion confirmed a multinucleated giant cell reaction to polarizable foreign material, consistent with foreign body granuloma. (C): Patient 6. Axial MRI, taken 3 months postsurgery, demonstrates two enhancing extraaxial nodules (one nodule shown) along the inferolateral aspect of the resection cavity in the right frontal lobe, without associated T2/FLAIR abnormalities but with centrally restricted diffusion on DWI, favored to represent postoperative foreign body granuloma. (D, E): Patient 3. Exuberant giant cell and histiocytic reaction to foreign material. Fibers have hollow, cylindrical profiles and birefringence under polarized light (E), consistent with cotton. (F, G): Patient 4. Exuberant foreign body giant cell, histiocytic, and eosinophil reaction to weakly periodic acid‐Schiff–positive nonpolarizable foreign material. Scale bar: 40 uM (D, E), 150 uM (F, G). Abbreviations: DWI, diffusion weighted imaging; IR‐FSPGR‐BRAVO, Inversion‐Recovery‐Prepared Fast‐Spoiled Gradient Recalled Brain Volume; T1 + C, contrast‐enhanced T1‐weighted; T2/FLAIR, T2‐weighted‐Fluid‐Attenuated Inversion Recovery.