Summary Pigmented Villonodular Synovitis (more recently termed tenosynovial giant cell tumor) is a locally aggressive neoplastic synovial disease (not a true neoplasm) characterized by joint effusions, expansion of the synovium, and bony erosions. The condition usually presents in patients between 30 and 40 years old with recurrent atraumatic knee hemarthrosis. Diagnosis is multifaceted with clinical assessment for joint effusion (most commonly the knee), MRI studies showing synovial expansion, arthrocentesis revealing a brown fluid, and biopsy revealing hemosiderin-stained multinucleated giant cells. Treatment generally consists of partial or total surgical synovectomy depending on presence of localized or diffuse PVNS. Epidemiology Incidence rare 9.2 per million per year in the United States Demographics most commonly in adults age 30-40 but can occur at any age equal incidence in men and women Anatomic location may occur locally (within a joint) or diffusely localized (intra-articular or classic form) anterior knee is the most common site of involvement (80%) login to view 1 more bullet knee > hip > ankle > shoulder > elbow diffuse (extra-articular extension) behaves differently from localized Etiology Pathophysiology pathobiology caused by an overexpression of CSF1 gene login to view 1 more bullet a locally aggressive neoplastic synovial disease (not a true neoplasm) Genetics mutations locations of chromosome 1p13 in majority of cases 5q33 chromosomal rearrangement Associated conditions Giant Cell Tumor of Tendon Sheath also known as pigmented villonodular tumor of the tendon sheath (PVNTS) Classification Localized versus Diffuse PVNS Characteristic Localized PVNS Diffuse PVNS Location Knee > hip > ankle Knee (75%) Age 30-50y <40y Gender Male = Female Female =/> Male Presentation Painless, swollen joint, longstanding Painful, swollen, tender, limited mobility Radiograph Osseous erosion from localized pressure Degenerative changes on both sides of the joint MRI Well circumscribed soft tissue mass Ill-defined (poorly circumscribed) soft tissue mass Recurrence 8% after synovectomy 30% after synovectomy Presentation History 50% of patients will have a prior history of trauma to the area Symptoms common symptoms insidious onsent of pain in affected joint stiffness in the affected joint swelling in the affected joint recurrent atraumatic hemarthrosis is hallmark of disorder Physical exam inspection joint effusion erythema palpation tenderness along joint line motion limited motion of affected joint Imaging Radiographs recommended views AP and lateral of affected joint findings soft tissue swelling may show cystic erosion with sclerotic margins on both sides of the joint CT indications to evaluate for extent of cystic bone loss findings may show cystic erosions on both sides of the joint similar to radiographs MRI indications most sensitive imaging study provides excellent delineation of both intra-articular and extra-articular disease findings reveals joint effusion, hemosiderin deposits, expansion of the synovium, and bony erosion low signal intensity on T1 login to view 2 more bullets low signal intensity on T2 "blooming artifact" login to view 2 more bullets extra-articular extension login to view 1 more bullet Studies Labs CRP and ESR often normal despite signs of soft tissue swelling Arthrocentesis indication recurrent hemarthrosis findings grossly bloody effusion Diagnostic arthroscopy indications gold standard for diagnosis synovial biopsy should be performed findings brownish or reddish inflamed synovium is typical of PVNS frond-like pattern of papillary projections Histology gross histology shows a proliferative mass extending from the synovium low power mononuclear stromal cells infiltrating the synovium highly vascular villi lined with plump hyperplastic synovial cells high power hemosiderin stained multinucleated giant cells pigmented foam cells (lipid-laden histiocytes) mitotic figures common Differential Synovial chondromatosis Hemophilia/hemarthrosis Rheumatoid arthritis Septic joints Other neoplasia Treatment Nonoperative observation indications login to view 1 more bullet CSF-1 receptor antagonist (pexidartinib) indications login to view 1 more bullet side effects login to view 1 more bullet Operative partial synovectomy indications login to view 1 more bullet technique login to view 2 more bullets total synovectomy +/- external beam radiation indications login to view 1 more bullet technique login to view 3 more bullets outcomes login to view 3 more bullets external beam irradiation login to view 4 more bullets total synovectomy and total joint arthroplasty indications login to view 2 more bullets total synovectomy and arthrodesis indications login to view 1 more bullet Techniques CSF-1 receptor antagonist (pexidartinib) technique oral medication taken once daily for 24 weeks showed significant improvement of PVNS disease burden in ~40% of patients. complications cholestatic hepatotoxicity was a noted side-effect of the drug Arthroscopic synovectomy of knee for PVNS approach routine arthroscopic portals for knee, ankle, and shoulder technique perform as thorough resection of synovium as possible through portals can be challenging to access the posterior portions of the joint or extra-articular disease Open posterior synovectomy of knee for PVNS approach posterior approach to the knee via transverse or S-shape incision across popliteal fossa approach between medial and lateral heads of gastrocnemius retract neurovascular bundle to access posterior joint capsule technique disease is often seen posterior and extra-articular to the knee complete posterior synovectomy and resection of extra-articular disease complications posterior approach to the knee places popliteal neurovascular bundle at risk Complications Recurrence incidence recurrence is the most frequent complication for both intra-articular and extra-articular disease login to view 3 more bullets Joint destruction moderate to severe joint deformity treatment may lead to the need for arthrodesis or amputation Skin necrosis, radiation induced sarcoma risk factors radiation therapy Prognosis PVNS is associated with a high rate of recurrence and accelerated degenerative changes of the knee ultimately requiring arthroplasty TKA in patients with PVNS is associated with complication rates