SAPHO syndrome.

Palmoplantar pustulosis and severe acne are sometimes associated with peculiar aseptic skeletal conditions, but such skeletal lesions can be found without skin lesions. The term SAPHO syndrome has been coined for this cluster of manifestations. (The acronym SAPHO refers to synovitis, acne, palmoplantar pustulosis, hyperostosis, and osteitis.) The most common site of the disease is the upper anterior chest wall, characterized by predominantly osteosclerotic lesions, hyperostosis, and arthritis of the adjacent joints. Osteosclerosis of the vertebral bodies, hyperostosis, and erosions of the vertebral plates can be encountered. Unilateral sacroiliitis is frequently observed. Long bone involvement consists of osteosclerosis or osteolysis with periosteal new bone formation. Peripheral arthritis can be present but is rarely associated with joint destruction. The pathogenesis of this syndrome remains unknown, but a link with seronegative spondyloarthropathies is probable. Radiologists should be aware of this unusual syndrome to avoid misdiagnosis (eg, tumor, infection), unnecessary surgery, and antibiotic therapy.