Andersson lesion in ankylosing spondylitis.

A middle-aged male patient developed acute back pain and a lumbar vertebral lesion following trivial physical trauma. The lesion was considered as tuberculous on vertebral x-rays and MRI. After biopsy of the lesion and spinal fixation, the patient was kept on empirical antituberculous treatment (ATT) to which he did not respond. On re-evaluation he was diagnosed to have an Andersson lesion in ankylosing spondylitis (AS). ATT was stopped and he was successfully managed by rest, steroids, methotrexate and sulfasalazine. A careful look at the patient's plain x-ray spine and awareness about the lesion can avoid misdiagnosis of this characteristic vertebral lesion found in AS.