Involvement of the axial skeleton is a characteristic feature of spondyloarthritis (SpA). Asymmetrical arthritis and enthesitis of the peripheral joints are found in about 30–60% of patients.^1–3

A 52-year-old patient with a history of psoriasis reported inflammatory back pain, painful ankles and knees and severe morning stiffness on admission. The physical examination revealed tender entheses at different locations: upper thoracic spine, lumbar spinous processes, both iliac crests and posterior superior iliac spines. Furthermore, there was tenderness of both sacroiliac joints, both knees and both ankles without joint swelling.

HLA-B27 antigen was negative. The sedimentation rate (70/76) and levels of C reactive protein (1.48 mg/dl) were increased. The Bath Ankylosing Spondylitis Activity Index was 6.0, and the Bath Ankylosing Spondylitis Functional Index was 4.6. Radiographs of the pelvis showed bilateral grade 3 sacroiliitis. Thus, ankylosing spondylitis (AS) associated with psoriasis was diagnosed. Treatment on admission comprised methotrexate (15 mg/week) and prednisolone (5 mg/day). Whole-body MRI (WB-MRI) was performed on a special 1.5 T scanner (Avanto, Siemens, Germany) for evaluation of the extent of suspected widespread inflammatory lesions. Images of the entire body, excluding the hands, were acquired in a head-to-toe scan using parallel imaging and a whole-body surface coil …