Pustulotic arthro-osteitis: defining the radiologic spectrum of the disease

Pustulotic arthro-osteitis (PAO) was termed by Sonozaki et al., who discussed the relationship between palmoplantar pustulosis (PPP) and osteoarticular inflammation. Manifestations of PAO are observed in the anterior chest wall, the spine, the pelvis, the sacroiliac joint, and the long bones. Hyperostosis is a radiological feature of PAO; furthermore, anterior chest wall involvement is common. The term SAPHO syndrome (SAPHO being an acronym for synovitis, acne, pustulosis, hypertostosis, and osteitis) has been coined to describe disease that manifests sterile inflammatory bone lesions together with skin eruptions. SAPHO syndrome groups together the following osteo-articular lesions that have been described as separate medical entities: chronic recurrent multifocal osteomyelitis (CRMO), PAO, and arthro-osteitis associated with a follicular occlusive triad. Osseous changes due to psoriasis vulgaris and generalized pustular psoriasis can be radiologically and clinically distinguishable from osseous changes due to PPP, acne, and CRMO as seronegative spondyloarthropathies.