Melorheostosis with recurrent soft-tissue components: a histologically confirmed case.

Melorheostosis is a very rare disorder characterized by irregular cortical thickening seen on radiographs. In this paper, we present a case of melorheostosis with microscopically confirmed soft-tissue components. The patient was a 51-year-old man who complained of severe pain in the lateral aspect of his right knee. The excision of an ossified soft-tissue lesion relieved intractable pain that had lasted 20 years. Microscopically, the cortex of the affected fibula was composed of thick compact bone and the soft-tissue component consisted of dense compact bone without endochondral ossification. The presence of soft-tissue osseous nodules around the joints is one of the specific conditions for melorheostosis and should be differentiated from synovial chondromatosis. The ossified soft-tissue lesion in our patient is to our knowledge the first reported case of the histologically confirmed soft-tissue component of melorheostosis, which differs from that of synovial chondromatosis.