A rare, benign rheumatologic disorder or syndrome characterized by hyperostosis and soft tissue ossification between the clavicles and the anterior part of the upper ribs. It is often associated with the dermatologic disorder palmoplantar pustulosis, particularly in Japan. Careful diagnosis is required to distinguish it from psoriatic arthritis, OSTEITIS DEFORMANS, and other diseases. Spondylitis of pustulosis palmaris et plantaris is one of the possible causes; also, evidence suggests one origin may be bone infection. Bone imaging is especially useful for diagnosis. It was originally described by Sonozaki in 1974.