Isthmic spondylolisthesis in pycnodysostosis

Pycnodysostosis is an inborn skeletal syndrome manifested by short stature with a concomitant spinal deformity and by dense sclerotic fragile bones. We report a 35-year-old woman with pycnodysostosis and isthmic spondylolisthesis. Pycnodysostosis should be added to the differential diagnosis of spondylolisthesis.