Pannus is thickened, invasive tissue formed from an inflamed synovium in rheumatoid arthritis. It creeps over the joint's cartilage and bone and releases enzymes that erode both — the mechanism behind the joint deformities seen in poorly-controlled rheumatoid disease. Modern early DMARD and biologic treatment aims to stop pannus forming in the first place, which is why the UK healthcare system refers suspected rheumatoid arthritis to specialists within weeks of symptoms.
What is pannus?
Pannus: Pannus is abnormal granulation tissue that grows in RA-affected joints, releasing enzymes that erode cartilage and bone. Early effective DMARD treatment prevents pannus formation and the resulting joint damage.
Last updated 2026-07-04. This is general information, not a substitute for personalised medical advice.