DIFFICULTIES IN THE DIAGNOSIS OF DIFFUSE IDIOPATHIC SKELETAL HYPEROSTOSIS (FORESTIER'S DISEASE)

Diffuse idiopathic skeletal hyperostosis, or Forestier's disease (FD), is a rare non-inflammatory disease of the locomotor apparatus, which is associated with ligament and tendon ossification that gradually results in ankylosis. In a number of cases, the clinical and radiographic patterns of FD are similar to those of ankylosing spondylitis (AS), which requires a differential diagnosis. The paper describes two clinical cases demonstrating difficulties in the differential diagnosis of FD and AS.