Postoperative Spinal 18 F-FDG PET Pseudoprogression Mimicking Malignancy.

A 60-year-old woman presented with left upper limb weakness. Spinal MRI revealed C2-C3 heterogeneous mass with no hypermetabolic foci on 18 F-FDG PET. Total resection was performed, and the pathology showed gliosis. Her limb weakness worsened 3 months after surgery. Spinal MRI revealed long intramedullary mass from medulla oblongata to C5, which showed obvious hypermetabolism under 18 F-FDG PET with an SUV max of 7.11, but 18 F-FET PET indicated mild hypermetabolism with an SUV max of 2.29. Malignancy was suspected, and C2-C4 biopsy was performed. The pathology results confirmed the diagnosis of gliosis, and the postoperative spinal 18 F-FDG PET results were considered pseudoprogression.