Pigmented Villonodular synovitis (PVNS)

30 yr old young lady with non specific pain knee joint.  MR shows well defined regular, intensely enhancing heterogenously altered signal intensity  lesion anterior to hoffas pad with presence of haemosiderin and  no bone involvement -  focal variety of PVNS is likely. Case submitted by Dr MGK Murthy and Dr Akshay Sahoo.

 Pigmented Villonodular synovitis (PVNS)

 Teaching points
Definition: benign proliferative disease of the synovium  affecting joints, bursae, and tendon sheaths(called giant cell tumour of tendons sheath)

Clinical: pain/ restricted  movements

Types: diffuse-common(Shag carpet type or fern like proliferation of synovium) ,  and rarer focal nodular form(sessile or pedunculated with no true capsule), usually monoarticular, knee (80%) , focal -small joints of hands and feet (commonest  soft tisue tumour of hand)

Xray---soft tissue swelling, no calcification, subchondral  saucerised erosions
CT- hyperdense (haemosiderin), enhancement
MRI- Modality of choice--- soft tissue enhancing swelling , crossing joints with no involvement of articular margins, haemosiderin on gradient sequences, subtle bright on T1 due to lipid laden macrophages and fat, secondary degeneraive changes