A case of SAPHO (synovitis-acne-pustulosis-hyperostosis-osteomyelitis) syndrome in which [18F]fluorodeoxyglucose positron emission tomography was useful for differentiating from multiple metastatic bone tumors.

We report the case of a 50-year-old Japanese woman with SAPHO (synovitis-acne-pustulosis-hyperostosis-osteomyelitis) syndrome. Radiographs showed osteosclerosis of the cervical and lumbar vertebrae, as well as osteosclerosis and osteolysis of the right femoral neck, resembling multiple metastatic bony lesions. Arriving at a diagnosis required hematological and imaging tests. Whole-body bone scintigraphy identified diffuse uptake from the lower cervical vertebrae to the lumbar vertebrae and marked uptake in the right femoral neck. However, with [(18)F]fluorodeoxyglucose positron emission tomography ([(18)F]FDG-PET) scanning, abnormal [(18)F]FDG uptake was not detected in cervical and lumbar spine, or in the femoral neck. Bone biopsy showed signs of chronic nonspecific inflammation, rather than tumor or infection. Based on these findings, the patient was diagnosed with SAPHO syndrome unaccompanied by skin lesions, and administration of non-steroidal anti-inflammatory drugs provided pain relief.