Occurrence of human leukocyte antigen B51-related ankylosing spondylitis in a family: Two case reports

Figure 2 Computed tomography image of the sacroiliac joint(s) of the two daughters who tested positive for human leukocyte antigen B51. A, B: Multiple small undulating lesions are apparent on both sacroiliac joints, suggesting grade 1 bilateral sacroiliitis were seen in one daughter; C, D: Small undulating lesions in both sacroiliac joints are apparent, suggesting grade 1 bilateral sacroiliitis in the other daughter. The lesions are indicated by the red circle.