Multimodality imaging of an unusual giant cell tumor of thoracic spine with mediastinal invasion: a case report.

Giant cell tumor (GCT) is a benign yet locally aggressive bone neoplasm typically situated in the juxta-articular metaphysis of long bones. Although spinal involvement is rare, it is predominantly reported in the axial skeleton, with the sacrum being the primary location. Conversely, GCTs are notably uncommon in the thoracic spine. In this report, we present computed tomography (CT), magnetic resonance imaging (MRI), and 2-Deoxy-2-[fluorine-18]-fluoro-D-glucose (¹⁸F-FDG) positron emission tomography combined with computed tomography (PET/CT) multimodality imaging findings of a 36-year-old woman diagnosed with a GCT of the thoracic spine. CT scans provide a precise evaluation of cortical thinning and penetration. While MRI lacks specific diagnostic indicators for GCT, it remains invaluable for delineating the extent of soft tissue expansion and the tumor's relationship with intraspinal neural elements - critical information for surgical planning. ¹⁸F-FDG PET/CT effectively illustrates the lesion's hypermetabolic and locally aggressive characteristics. It is noteworthy that GCT occasionally exhibits metastatic malignant potential, underscoring the value of FDG PET as a pivotal modality for staging, restaging, or assessing therapy response, and for monitoring the efficacy of radiotherapy. Familiarity with the imaging features of GCT is essential for physicians to avoid misinterpretation. This tumor should be considered in the differential diagnosis of spinal tumors, distinguishing it from bone metastases or neurogenic tumors.