1) Plain radiography

- Anteroposterior radiograph of thoracic spine shows poorly-defined osteolysis with pathologic compression at T11 body.

2) CT

- Axial CT image shows expansile, markedly osteolytic lesion in body, both pedicles, and left transverse process of T11.

3) MR

- Sagittal T1-weighted fast spin-echo MR image shows homogeneous low signal intensity except vertical low signal area. Sagittal T2-weighted fast spin-echo MR image shows heterogeneous hyperintensity and vertical low signal area within mass. Contrast-enhanced axial T1-weighted fast spin-echo MR image shows heterogeneous enhancement. Vertical low signal area on T1- and T2-weighted images did not reveal any enhancement.

Differential Diagnosis:

Giant cell tumor, osteoblastoma, eosinophilic granuloma, plasmacytoma, metastasis

Diagnosis: Giant cell tumor

Discussion:  Seven percent of giant cell tumors occur in the spine. The sacrum is affected in 90% of such cases. Above the sacrum, the lumbar, thoracic, and cervical spine (in decreasing order of frequency) may be affected. The tumor usually predominates in the vertebral body, with frequent involvement of the posterior arch. Destruction of a vertebral body is more frequent than destruction of the posterior osseous elements (differing from the posterior involvement that characterizes an aneurismal bone cyst or osteoblastoma). Extraosseous involvement of the soft tissues is seen in 79% of cases. Intervertebral disk invasion and extension into an adjacent vertebra is possible.

 Radiography typically shows a lytic lesion with cortical expansion. A purely osteolytic pattern is also possible. CT demonstrates absence of mineralization and the lack of a sclerotic rim at the margins of the tumor. The tumor usually has low to intermediate signal intensity on T1-weighted MR images. Areas of high signal intensity can suggest relatively recent hemorrhage. More specifically, most giant cell tumors of the spine have low to intermediate signal intensity on T2-weighted images. This appearance seems to be caused by hemosiderin deposition and high collagen content. Enhancement of the lesion reflects its vascular supply. Cystic areas, foci of hemorrhage, fluid-fluid levels, and a peripheral low-signal-intensity pseudocapsule may also be seen.

References:

1. Resnick D. Diagnosis of bone and joint disorders. Saunders, 2002, 4^th ed. P3939-3962

2. Rodallec MH, Feydy A, Larousserie F, etc. Diagnostic imaging of solitary tumors of the spine: what to do and say. Radiographics 2008;28:1019-1041

3. Kwon JW, Chung HW, Cho EY, etc. MRI findings of giant cell tumors of the spine. AJR Am J Roentgenol. 2007;189:246-250