Tenosynovial giant cell tumour: current concepts review and recent developments focusing on pathogenesis and treatment-directed classification

Abstract

Tenosynovial giant cell tumour (TSGCT) is a benign, aggressive tumour arising from joint synovia, bursae and tendon sheaths. The majority of cases are localised, presenting with a localised lesion of the synovium, with 10% of presentations being of a diffuse-type synovial involvement. These can be associated with severe morbidity and a risk for malignant transformation. Recent developments in the pathogenesis originating from inflammatory and potentially neoplastic sources have highlighted the involvement of various  chromosomal abnormalities, including chromosomes 1, 3, 5, trisomy 7, and trisomy 5. Additionally, the overexpression of colony- stimulating factor 1 (CSF-1) and the recruitment of its receptor (CSF-1R) on immune cells, osteoclasts and giant cells have emerged as significant factors. These developments suggest that biologic agents hold great promise as a future treatment modality, particularly for cases associated with severe morbidity. Tyrosine kinase inhibitors, particularly pexidartinib, a CSF-1R antagonist, and imatinib are further discussed in some detail. Finally, we explore the role of arthroscopic synovectomy and a recently developed treatment-directed classification for TSGCT in the localised type as a standalone procedure. The diffuse types require combination with other approaches.

The key concepts are as follows:
• Information regarding TSGCT is sparse.
• TSGCTs can be diffuse, which is associated with severe morbidity.
• New insight regarding the involvement of chromosomal involvement and the overexpression of CSF-1 has directed the use of biologics such as tyrosine kinase inhibitors for severe cases.
• A useful and practical treatment-directed classification of TSGCT has recently been developed.