An 81-year-old woman with history of thyroiditis and a putative diagnosis of retroperitoneal fibrosis presented with abdominal pain, progressive shoulder pain, back pain, and lower extremity weakness. Abdominal and pelvic MRI revealed periaortic inflammation and a left renal mass, which were 18F-FDG avid on PET/CT. Renal biopsy was compatible with immunogammaglobulin 4 (IgG4)–related disease. Total spine MRI revealed postcontrast meningeal enhancement, correlating with FDG activity. Epidural biopsy showed chronic inflammation and scattered but not abnormal IgG4-positive cells, possibly related to posttreatment changes. This case exemplifies multiorgan involvement in IgG4-related disease.