The authors describe a patient who had Gorham-Stout syndrome involving the lumbar spine. This syndrome, which also is called vanishing bone disease or idiopathic massive osteolysis, is a rare and generally unifocal disorder, seen in young adults (about 140 patients reported). Involvement of the lumbar spine is not frequent (3 patients reported) and has a worse prognosis because of late neurological complications. The pathogenesis is incompletely known. The diagnosis is made with biopsy (bony lymphangiomatous changes on microscopy). The clinical evolution is unpredictable. Complications depend on the affected bones (neurological or pulmonary).