Pigmented villonodular synovitis (PVNS) is a benign synovial proliferative condition marked by synovial metaplasia and hypertrophy with deposits of hemosiderin-laden macrophages.
PVNS is part of a disease spectrum that includes localized and diffuse forms of Tenosynovial Giant Cell Tumour (TGCT) .
Intraarticular PVNS is usually a diffuse synovial process, but a nodular localized type of PVNS has also been reported.
PVNS usually affects adults between the ages of 20 and 50 years
Children can be affected but this is rare
Men and women are equally effected
Patients frequently complain of gradually progressing pain
swelling, or a palpable mass and reduced range of motion.
A history of recurrent and bloody joint effusion is another typical clinical feature, especially in diffuse disease.
Treatment options include surgical resection, radiation therapy and pharmacological treatment
Local disease typically requires only surgical resection and recurrence rates are low
Diffuse articular involvement is more difficult and is
Complicated by frequent recurrence
Imaging findings include joint effusion or a synovial mass with hemosiderin deposits.
Bone erosions of variable size may occur, the prevalence depends on joint capacity.
Erosions are seen in about 25 % of cases in the knee but around 80% in the hip or shoulder
Osteopenia is common but joint space loss is late
The localised nodular form of PVNS is almost exclusively seen in the knee
Presentations include pain, a palpable mass, and locking.
Common locations are the infrapatellar fat pad , the suprapatellar pouch or the intercondylar notch
SYNOVIAL OSTEOCHONDROMATOSIS
The primary disease is characterized by synovial proliferation and the formation of round cartilaginous or osteocartilaginous bodies
It lies between a chondroid metaplasia and a benign neoplastic condition, but subject to recurrances
Primary synovial osteochondromatosis may affect joints, tendons, or bursae.
Affects the knee and less frequently the hip, shoulder or elbow but any joint may be involved
Men between the ages of 30 and 50 years are affected
Presents with gradual onset of pain and limitation of movement over a period of months or years
Malignant transformation is recognised but rare
Imaging demonstrates calcification in 90%
Evenly distributed and of similar size, or ring and arc pattern with a peripheral rim and a central dot of calcification or a giant mass
..called giant osteochrondroma.
10 % without calcifications may be difficult to distinguish from other causes of synovial hypertrophy.
The appearance on MRI depends on the stage of synovial proliferation, loose body formation and the extent of calcification or ossification.
Jjoint effusion, lobulated mass with calcification
Foci of calcification within these appear as lowsignal regions which show less blooming than PVNS .
Like PVNS erosions are more common in low capacity joints such as the hip
Can extend into adjacent bursae which must be eradicated to prevent recurrence
Mimics include rice body arthritis, TB and occasionally RA
Rice bodies are isointense on T1
SYNOVIAL CHONDROMA
Synovial chondroma or paraarticular chondroma is a variant of synovial osteochondromatosis.
It is solitary and also arises as a result of cartilaginous metaplasia
The lesions can ossify and are then called osteochondromas
There are most common in the infrapatellar fat pad, but can also be found in the suprapatellar pouch and the hip or elbow
SYNOVIAL HEMANGIOMA
Synovial hemangioma is a rare vascular lesion that arises in the sub-synovial membrane
They are composed of varying amount of fat, fibrous tissue and thrombus
It mainly affects children and adolescents, but is occasionally seen in older adults
60% occur in the knee
; this is the site of disease in approximately 60 Patients present with pain, swelling, and recurrent hemarthrosis.
Radiographs iare usually normal but may show a soft tissue mass with effusion
Phleboliths are not common unless the lesion extends beyond the joint margin
Other findings include erosions, periosteal reaction, and bone destruction
MRI features include a lobulated soft tissue mass, with signal voids and a lobulated margin
Fat and vascular channels suggest the diagnosis
They enhance homogenously after the administration of gadolinium.
Synovial hemangioma mimics hemophilic arthropathy within the knee
