Giant-cell tumor of the tendon sheath involving the thoracic spine.

Giant-cell tumor of the tendon sheath is a common benign lesion of the synovial membrane that frequently occurs in the hand. It is related to pigmented villonodular synovitis and the occurrence of pigmented villonodular synovitis or giant-cell tumor of the tendon sheath in the axial skeleton is very rare. To data, only three cases of giant-cell tumor of the tendon sheath involving cervical spine have been reported, compared with 26 cases of pigmented villonodular synovitis. Pigmented villonodular synovitis involving the thoracic spine is also extremely rare and our case represents the first reported case of a giant-cell tumor of the tendon sheath involving the thoracic spine. A 26-year-old man presented with left back pain without neurological deficit. Computed tomography and magnetic resonance imaging (MRI) revealed an osteolytic and expansive lesion in the left facet joint between the seventh and eighth thoracic vertebrae. A complete facetectomy and excision of the lesion followed by a posterior arthrodesis between Th5 and Th9 was performed. Postoperatively, the patient recovered with complete relief of symptoms, there was no evidence of recurrent disease or regrowth of the residual lesion, as investigated by plain radiographs and MRI within a follow-up period of two years. Although giant-cell tumor of the tendon sheath in the thoracic spine may be extremely uncommon, it should be considered in the differential diagnosis, especially when a benign lesion appears to originate in the face joint. Considering the high rate of recurrence, every effort should be made to achieve total excision.