Fibrous dysplasia - thoracic spine

An expansile lytic lesion involving T6 and T7 vertebrae contagiously with loss of vertebral architecture and vertebral body expansion with a 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. Associated focal kyphotic deformity with the apex at the T6/7 level without 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.

Rib involvement:

• 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 with the 6^th and 7^th vertebrae and absence of the proximal parts of their bodies (given history of previous surgical intervention)

Replaced matrix of T6 and T7 vertebrae showing T1 isointense signals with areas of hyperintensity, T2WI hyperintensity with loculations showing fluid levels reflecting hemorrhagic components. The lesion has a paravertebral component, larger on the right side. It extends also to the spinal canal forming an extra-dural component markedly compressing the spinal cord at the same level.