Bone Involvement Mimicking an Aggressive Bone Lesion in a Diffuse-type Tenosynovial Giant Cell Tumor in the Thoracic Vertebral Lamina: A Case Report

INTRODUCTION: Diffuse-type tenosynovial giant cell tumor (D-TGCT), or pigmented villonodular synovitis, is a benign, but aggressive lesion, primarily involving large joints. The spine is rarely affected, with the involvement of the thoracic spine being particularly rare. Massive bone involvement associated with facet joints is a characteristic of spinal D-TGCT. CASE REPORT: We report the case of a 26-year-old woman with D-TGCT in her first thoracic vertebral lamina. Computed tomography (CT) showed an osteolytic expansive lesion without the involvement of the facet joint. Magnetic resonance imaging (MRI)revealed a lesion with intermediate signal intensity on T1- and T2-weighted images. After computed tomographically guided biopsy, curettage was performed, and D-TGCTwas diagnosed. CONCLUSIONS: Features of CT and MRI suggested an aggressive bone lesion, and it was challenging to assume D-TGCT, particularly without the involvement of the facet joint.