¹⁸F-FDG PET/CT imaging and clinical features of SAPHO syndrome

Objective: To analyze the ¹⁸F-FDG PET/CT imaging and the clinical features of patients with synovitis, acne, pustulosis, hyperostosis, and osteitis(SAPHO) syndrome and improved the diagnosis and awareness level about the disease. Methods: This study retrospectively analyzed the PET/CT images and clinical features of five patients(including 3 females and 2 males; age range: 59-74 years old; average age: 67.2 years old) with SAPHO syndrome, as well as reviewed relevant literature. The PET/CT examinations were performed from March 2011 to August 2013. SAPHO syndrome was diagnosed through biopsy, imaging, follow-up results, and according to the Kahe Standard. Results: (1) Clinic: Five patients sought treatment in the hospital for bone joint pain or skin lesions. Two of the five patients had no skin lesions, three patients exhibited elevated serum CRP and ESR levels, and one patient was positive for HLA-B27. Rheumatoid factor, extractable nuclear antigen peptide antibody spectrum and antineutrophil cytoplasmic antibodies were negative in 5 patients. The average diagnosis period was 3.78 years. (2)PET/CT imaging: Five patients showed anterior chest wall and spine involvement. Anterior chest wall involvement included 11 bone joints, such as the sternoclavicular joint, sternocostal joint, and sternal-body joint. One patient showed hypertrophy and osteomyelitis of the clavicle. Only one patient showed an involvement of a single vertebra, whereas the others showed an involvement of multiple sites of the spine, including 35 vertebra and 58 vertebral disc connections. The CT revealed the worm-eaten and hole-shaped bone destruction on the articular surface of the anterior chest wall and intervertebral disc junction. They were surrounded by relatively extensive osteosclerosis, even involving the entire vertebral body. The partially involved joints also showed joint space narrowing and even joint bone fusion. In addition, swelling, thickening, and calcification of periarticular soft tissues were observed. The PET revealed that only a part of the involved bone joints of anterior chest wall lesions(6/11) and intervertebral disc junctions(17/58) exhibited an increased ¹⁸F-FDG uptake, and the SUV_max ranged from 1.76 to 9.74. ¹⁸F-FDG uptake of the other involved bone joint lesions was similar or lower than that of the adjacent similar organization. The clavicle with hypertrophy and osteomyelitis in the patient showed an ¹⁸F-FDG uptake SUV_max of 2.68. Conclusions: The anterior chest wall and spine are the common sites of involvement in SAPHO syndrome patients with or without skin lesions. ¹⁸F-FDG PET/CT scan can reveal more occult lesions and active inflammation as well as effectively exclude neoplastic lesions. (authors)