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Neoplastic lesions

TGCT is a reactive, inflammatory neoplasm, although originally it was regarded as a nontumoral process.1,3,4

Molecular pathogenesis

As explained above, pathogenesis of TGCT is believed to start when a small number of neoplastic cells that arise from the lining of the synovium overexpress a growth factor called CSF-1. In most patients, CSF-1 overexpression is reported as a result of a genetic translocation.1,2

Tumor landscape

Typically, TGCT tumors are composed of a small number of these neoplastic cells (2% to 16%) and a high number of CSF-1R–expressing myeloid-lineage cells, including monocytes and macrophages, recruited through CSF-1 signaling.1,3

CSF-1 and TGCT formation and progression

Neoplastic cells

Autocrine stimulation
CSF-1 may activate CSF-1R in cells within
the tumor, resulting in the proliferation of neoplastic cells.1

Macrophage and Monocyte cells

Paracrine effect
CSF-1 may recruit CSF-1R–expressing myeloid-lineage cells that comprise
the majority of the tumor mass.1

Tenosynovial Giant Cell Tumor

TGCT morbidity
CSF-1 overexpression may also contribute
to the inflammation and osteochondral destruction seen in some cases of tenosynovial giant cell tumor (TGCT)
within the affected joint.2,5

View signs and symptoms by subtype.   arrow-right


  1. West RB, Rubin BP, Miller MA, et al. A landscape effect in tenosynovial giant-cell tumor from activation of CSF1 expression by a translocation in a minority of tumor cells. Proc Natl Acad Sci U S A. 2006;103(3):690-695. doi:10.1073/pnas.0507321103
  2. Cupp JS, Miller MA, Montgomery KD, et al. Translocation and expression of CSF1 in pigmented villonodular synovitis, tenosynovial giant cell tumor, rheumatoid arthritis and other reactive synovitides. Am J Surg Pathol. 2007;31(6):970-976. doi:10.1097/PAS.0b013e31802b86f8
  3. So-called fibrohistiocytic tumours. In: Fletcher CDM, Bridge JA, Hogendoorn PCW, Mertens F, eds. WHO Classification of Tumours of Soft Tissue and Bone. 4th ed. International Agency for Research on Cancer; 2013:99-108. Bosman FT, Jaffe ES, Lakhani SR, Ohgaki H, eds. World Health Organization Classification of Tumours; vol 5.
  4. Gouin F, Noailles T. Localized and diffuse forms of tenosynovial giant cell tumor (formerly giant cell tumor of the tendon sheath and pigmented villonodular synovitis). Orthop Traumatol Surg Res. 2017;103(1S):S91-S97.
  5. Ota T, Urakawa H, Kozawa E, et al. Expression of colony-stimulating factor 1 is associated with occurrence of osteochondral change in pigmented villonodular synovitis. Tumor Biol. 2015;36(7):5361-5367. doi:10.1007/s13277-015-3197-5