Imaging for Synovitis, Acne, Pustulosis, Hyperostosis, and Osteitis (SAPHO) Syndrome

Multifocal osteomyelitis and synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome constitute a spectrum of disease that includes inflammatory bone lesions and dermatologic findings. Radiographic features resemble those of the spondyloarthropathies with anterior chest wall involvement. Early radiographic findings are osteodestructive with lytic lesions. Bone scintigraphy of the sternoclavicular region classically yields a 'bull's head' pattern of radionuclide uptake. Magnetic resonance imaging (MRI) can demonstrate corner lesions of vertebral bodies. Ultrasound often reveals peripheral enthesitis. Late radiographic features are usually osteoproliferative. PET/CT can identify chronic lesions. Differential diagnostic considerations include osteomyelitis and malignancy, which often prompt bone biopsy.