The biopsy consists of scanty material formed dominantly of unremarkable fibrofatty tissue with synovial lining with focal tiny fragments of hyperplastic synovium showing mild synoviocyte proliferation and a sparse chronic inflammatory infiltrate. Within the stroma, focal aggregates of hemosiderin-laden macrophages are identified, consistent with the clinical history of chronic effusion. There is no evidence of the diffuse sheet-like growth of mononuclear cells, foamy macrophages, or multinucleated giant cells characteristic of classic Pigmented Villonodular Synovitis (PVNS) in the provided material, and no malignancy is seen.
Chronic knee effusion undergoing arthroscopic evaluation for suspected Pigmented Villonodular Synovitis.
Soft tissue fragments collectively measured 1x0.8xx0.3 cm, totally embedded.
Knee joint, synovial biopsy: