Mondo Description Isolated sternocostoclavicular hyperostosis is a rare rheumatologic disease characterized by predominantly bilateral, chronic, sterile inflammation and progressive sclerosis and hyperostosis of the sternocostoclavicular joint, with adjacent soft tissue ossification, in the absence of other joint involvement. It presents as recurrent episodes of pain, edema and/or erythema of the sternoclavicular region. Palmoplantar pustulosis may be additionally observed in some cases.