Foreign Body Granuloma After Embolization of Internal Iliac Artery Aneurysm Using N-Butyl-2-Cyanoacrylate: A Case Report.

Foreign body granulomas following endovascular treatment are rare complications and are mostly reported in the brain or cutaneous vascular tissues. To the best of our knowledge, no study to date has reported on foreign body granulomas in the abdomen after injection of N-butyl-2-cyanoacrylate (NBCA)-lipiodol mixture into the abdominal arteries. This study reports a case of foreign body granuloma that appeared 12 months after the embolization of a right internal iliac artery aneurysm using an NBCA-lipiodol mixture, which posed challenges in differentiation from malignant tumors. We present a 77-year-old man who underwent embolization of a right internal iliac artery aneurysm and open surgical repair of an abdominal aortic aneurysm. A contrast-enhanced CT performed 12 months postoperatively revealed a right-sided retroperitoneal mass surrounding the iliopsoas muscle. The mass contained multiple, small, hyperdense areas, suggesting the migration of the NBCA-lipiodol mixture casts from the embolized right internal iliac artery aneurysm. The differential diagnosis included foreign body granuloma, lymphoma, and sarcoma. A biopsy of the lesion revealed a granuloma with various stages of inflammation, no hemosiderin deposition, multinucleated giant cells, and foam cells containing fat, and was diagnosed with a foreign body granuloma. Special staining for microorganisms revealed no findings suggestive of infection. Because the patient was asymptomatic, no treatment was administered. Contrast-enhanced CT at 24 months postoperatively showed shrinkage of the mass, with no change in size noted at 48 months postoperatively. This report highlights a foreign body granuloma that mimicked malignant tumors. Extravascular migration of the NBCA-lipiodol mixture casts likely contributed to granuloma formation. Radiologists should consider foreign body granulomas after embolization using NBCA into the abdominal arteries.