Multiple painful bone cysts in a young man.

To confirm the diagnosis of diffuse cystic angiomatosis, it is necessary to biopsy the bone: the walls of the cysts react to immunological markers of the endothelium (antigens related to factor VIII and CD31). Alternatively, lymphography can avoid the necessity for biopsy. Evolution of the condition is variable and depends on the extent of visceral involvement, and usually the extent of soft tissue and visceral involvement dictates the morbidity and mortality. There is no specific treatment, though osseous lesions can regress spontaneously.