Home > E. Pathology by systems > Locomotory system > Tendons and tendon sheaths > villonodular tenosynovitis
villonodular tenosynovitis
Saturday 19 December 2020
Tenosynovial giant cell tumour, diffuse type
| PO |
Synopsis
diffuse expansive sheets of cells with infiltrative borders and variable cellularity;
tumor margins are more cellular
hyperplastic synovium with papillary projections composed of foamy histiocytes and hemosiderin containing macrophages
large clefts, pseudoglandular or alveolar spaces lined by synovial cells, osteoclast-like multinucleated (10 - 70 nuclei) giant cells, epithelioid cells
abundant collagen may be present, but lymphocytes and plasma cells are sparse
giant hemosiderotic granules (2 - 3x diameter of RBC), giant siderophages (Pathologe 2005;26:96)
May have 5+ mitotic figures / 10 HPF, rarely chondroid metaplasia (Mod Pathol 2007;20:545)
Malignant if nodular and solid invasive growth plus large cells with large nuclei, prominent nucleoli, necrotic areas and atypical mitotic figures
Differential diagnosis
hemosiderotic synovitis
associated with hemophilia and intraarticular bleeding,
no mononuclear or giant cell nodular proliferation,
hemosiderin primarily in synovial lining cells