The spine in fibrodysplasia ossificans progressiva: a case report.

Study Design: A case report of fibrodysplasia ossificans progressiva (FOP).

Objectives: To report a very rare cause of back pain.

Summary Of Background Data: FOP is an autosomal dominant disorder with overexpression of bone morphogenetic protein 4 and negative HLA B27. Pathognomonic are congenital malformations of the big toes.

Methods: The authors report on a patient with FOP who presented with back pain at their outpatient clinic.

Results: On physical examination, several indurated masses were visible and palpable close to the left and right scapula and the thoracic spine. These were not tender or painful, nor warmed or inflamed. A significantly decreased range of motion of all levels of the spine and the shoulder were found. On the radiographs, segmentation defects of the cervical and lumbar spine as well as synostoses of the spinal processes were seen. The cervical vertebral bodies were small and unusually high. Heterotopic ossifications could be discerned in the lumbar postural muscles and the facet joints of the spine were ankylosed. Additionally to these findings, on the thoracic radiographs ossifications of the muscles of the shoulder girdle could be seen. The pathognomonic shortening of the first metatarsal bone and the proximal phalanx was bilaterally present. The surface shaded 3D-reconstruction of the computed tomography of the trunk showed multiple bulky and confluating ossifications of the shoulder girdle. The spinal processes of the thoracic spine were anklyosed by massive ossifications of the postural muscles.

Conclusions: In FOP, diagnosis can be made by the typical clinical and radiological features.