A 49-year-old woman complained of right upper back pain for 1 month. Serum tests showed increased erythrocyte sedimentation rate. Thoracic spinal MRI showed an epidural lesion at the T1–T4 level with inhomogeneous signal intensity on T2-weighted images, slightly higher signal intensity than spinal cord on T1-weighted images, and remarkable enhancement on enhanced T1-weighted images. Epidural malignant tumor was suspected. FDG PET/CT was performed showing increased FDG uptake of the lesion extending to the right T1–T2 and T2–T3 neural foramina. A decompressive posterior thoracic laminectomy with the lesion resection was performed. Immunoglobulin G4–related spinal hypertrophic pachymeningitis was confirmed by pathology.