Gorham's disease is a rare bone disorder characterized by bone loss (osteolysis), often associated abnormal blood vessel growth (angiomatous proliferation). Bone loss can occur in just one bone, or spread to soft tissue and adjacent bones. Symtoms may include pain, swelling, and increased risk of fracture. It may affect any part of the skeleton, but most commonly involves the skull, collarbone (clavicle), pelvis, ribs, spine, and/or jaw. Depending on the bones affected, various complications may occur. The cause of Gorham's disease is currently unknown. Most cases occur sporadically.