Fibrous dysplasia - thoracic spine

An expansile lytic lesion is noted involving T6 and T7 vertebrae contagiously with loss of vertebral architecture and vertebral body expansion with thin expanded bony cortical outline showing multiple defects secondary to expansion. The expansion is affecting the entire vertebral components, more involving the right side of the vertebral bodies and right transverse processes with more bulge towards the right side encroaching upon the dorsal spinal canal and related right sided dorsal nerves, notably at T6/7 level bilaterally, with marked compression upon the right T6/7 exiting nerve root. The overall formed mass lesion is measuring 7.8 x 7.5 x 6.2 cm in AP, SS and CC dimensions respectively. Related focal kyphotic deformity is noted with apex at T6/7 level. No associated scoliosis. These effects are accentuated by the involvement and expansion of the spinous processes of the involved vertebrae with mass effect along the related dorsal spinal cord at the same levels posteriorly. It is also extending to the right side of the related posterior mediastinum compressing the azygos vein. No other dorsal spine affection noted.

Rib involvement:

• The lateral aspect of the left 6^th rib body.

• The bodies of the right 6th, 7^th and 8^th ribs with rib expansion exerting secondary diminished volume of the right lung lobe.  Fusion of the 6^th and 7^th vertebrae is noted with missing the proximal parts of their bodies; given history of previous surgical intervention.

Features of polyostotic expansile benign bone disease; known polyostotic fibrous dysplasia with the above-described involvement and mass effect of the thoracic spine involvement and secondary aneurysmal bone cyst change of the thoracic spine lesion. Fibrous dysplasia occurs rarely in the spine, especially in the thoracic spine. Fibrous dysplasia of the spine usually occurs as a part of the polyostotic form of the disease.

See case (rID-42871) for craniofacial manifestations in this patient.