Sections show fragments of fibro-adipose tissue and fibrotic synovium shows focal ulceration and dense infiltration by lymphocytes, plasma cells and macrophages with neutrophils. There is associated capillary proliferation and mild tissue edema. No evidence of specific granulomas. No evidence of atypia or malignancy.
Rt knee lesion.
Soft tissue fragments collectively measured 2.3x2x0.8 cm, totally embedded.
Knee swelling, biopsy: