A case of osteomalacia mimicking ankylosing spondylitis

A 39-year-old woman presented with symptoms of pain in the lumbar region and lower extremities. Physical findings included restricted movement of the lumbar spine, sacroiliac joint tenderness, positive Schober's test (10–12.5 cm), and bilaterally positive Mennel and Fabere tests. Although these symptoms and findings were suggestive of ankylosing spondylitis, osteomalacia was diagnosed with the appearance of multiple pseudofractures in her pelvic X-ray and laboratory abnormalities. All her symptoms and signs resolved in 6 months with vitamin D and calcium treatment.