Pigmented villonodular synovitis (PVNS), is a locally destructivefibrohistiocytic proliferation that is characterized by many villous andnodular synovial protrusions , which affects joints, bursae, and tendonsheaths .The etiology is unknown and is often controversial , someinvestigators have suggested an autoimmune pathogenesis, trauma,disturbance in lipid metabolism, an inflammatory response to anunknown agent, or benign neoplasms.PVNS is a benign condition but its problem lies with: difficult todiagnose early as symptoms are nonspecific and present late, difficult todifferentiate from other conditions such as Rheumatoid arthritis,Osteoarthritis, inflammatory, neoplastic diseases of the synovium andhigh incidence of recurrence after surgical treatment.Imaging plays an important role in the diagnosis of PVNS ; PlainX- Rays reveal a soft tissue density in the affected joint, erosion ofsubchondral bone with a sclerotic margin. MRI is extremely useful inmaking a diagnosis because on T2 – weighted images the intraarticularmasses demonstrate a combination of a high-signal-intensity areas,representing fluid and congested synovium, interspersed with areas ofintermediate to low signal intensity, secondary to random distribution ofhemosiderin in the synovium .Treatment options may include: Synovectomy which may be openor arthroscopic also some authors included physical adjuvants in theirtreatment protocols in order to decrease the rate of recurrence. Radiationsynovectomy/radiosynoviorthesis.Recently- blockade with infliximab has been reported as aneffective therapy also there might be a role for specific inhibitors ofRANKL proteins in the treatment of PVNS.