Recently, in clinical teaching, a patient brought X-rays of the lumbar spine and MRI of the lumbar spine to ask what was going on, and a student asked if the oval shadow on the MRI film was a tumor after reading the film. …… This is a patient with ankylosing spondylitis. Figures 1 and 2 show that the lumbar spine has become a bamboo-like change, because ankylosing spine is characterized by calcification of the ligaments around the spine and osteoporosis of the vertebral body, and the cartilage plate constituting the intervertebral disc can be damaged. Because the ligaments around the vertebral body have been calcified, the nucleus pulposus of the intervertebral disc can only protrude into the vertebral body in the event of cartilage plate defects. Since the density of the nucleus pulposus is lower than that of the bone, the elliptical hypodensities seen between the two vertebrae in the third and fourth pictures are not tumors or tuberculosis.