Lumbosacral Paravertebral Tophaceous Gout on an Adolescent Mimicking Malignant Neoplasm in 18F-FDG PET/CT

Abstract

Contrast-enhanced MRI was performed on a 17-year-old adolescent boy with chronic lumbar and lower-limb pain, which had worsened over the past 3 days. It revealed a suspicious malignant mass adjacent to right appendage of L5–S1 vertebrae, with mixed signals and heterogeneous and obvious enhancement. 18F-FDG PET/CT was subsequently performed for staging. It showed an FDG-avid mass with mixed density in right psoas major muscle, involving adjacent appendage of L5–S1 vertebrae. Histopathological examination confirmed the mass to be gouty tophus, characterized by nodular homogeneous pink amorphous deposits around the cartilage tissue, surrounded by histiocytes and multinucleated giant cells.