Fibrous dysplasia of the cervical spine presenting as a pathological fracture.

Fibrous dysplasia (FD) is an uncommon benign fibro-osseous abnormality of bone, of unknown aetiology and equal sex incidence, which is most commonly restricted to one bone (monostotic FD: MFD, 70%). Less commonly multiple bones are affected (polyostotic FD: PFD, 27%). Vertebral involvement is uncommon (4%), but more common with PFD (7 - 24%) than MFD (1%). Of 20 cases of FD involving the cervical spine, only three have represented MFD. Unlike cases associated with PFD, all cases presented with acute neck pain without significant neurological impairment after minor trauma. We present the case of a 35-year-old male with MFD who developed a pathological fracture of C3 following minor trauma. Radiographs showed collapse and typical 'ground glass' lucency of C3. CT revealed replacement of C3 cancellous bone by hypodense tissue extending into the right lateral mass. The cortex was thinned and fractured, and encroached upon the right foramen transversarium and spinal canal. Magnetic resonance imaging demonstrated hypo-intensity on both T1 and T2, with uniform contrast enhancement. Subtotal excision was achieved via an anterior C3 corpectomy, with residual FD left within the right lateral mass. Stability was achieved utilizing an iliac crest strut autograft, C2-4 plate-and-screws, and mobilization in a halo frame for 3 months. At 18 months, he remained asymptomatic and without deficit. Radiography, CT and MRI confirmed graft fusion without FD invasion, but with residual right lateral mass FD unchanged in size.