[Low back pain--the relevance of a symptom].

Low back pain is one of the main reasons for doctor's appointment, and the motive of consultation of General Practitioners in 56% of cases. More than 85% of the patients who present to primary care physicians have low back pain that cannot reliably be attributed to a specific cause. In a minority of cases low back pain can be caused by a specific disorder, such as cancer. The authors describe a case of a 59-year-old woman with prolonged evolution low back pain which turned out to be a high grade osteossarcoma of the iliac bone.