Young adults 15-35.
The lesion does not arise from the synovium.
Alternate names include carcinosarcoma or spindle cell carcinoma of soft tissue.
The majority are in the extremities, the lower limb is affected the most.
10% are intra-articular.
One third demonstrate calcification, usually in the periphery.
Multiloculated with septations.
Triple signal related to cyst haemorrhage and necrosis which in conjunction with haemorrhage in a young individual supports the diagnosis.
Margins are usually well defined
A mono-arthritis of the knee due to synovial metaplasia similar to synovial osteochondromatosis.
20-40 age group
Same sex distribution
Theories include repeated trauma, a viral aetiology, a lipid disturbance or a histolytic response to an unknown stimulus.
The plain film may suggest synovial disease although these can be subtle
Bone changes are present in 90% of patients with PVNS.
Preservation of bone density until relatively late.
Cartilage loss is also late
Traction spurs and osteophytes are uncommon.
MRI is the main stay for diagnosis of PVNS.
Haemosiderin deposition shows as low signal material on T2
Prominent blooming on T2* also helpful
The principal difference with diagnosis on PVNS is synovial osteochondromatosis.
whenever PVNS is considered as a differential diagnosis, synovial osteochondromatosis (SOC) should also be considered.
The disease occurs in a very similar age group and a
similar clinical presentation to PVNS.
Both conditions are non malignant synovial metaplasias.
Phases of involvement are identified of both conditions although these are more obvious in SOC.
Three phases are described,
• the early active phase which is predominantly a synovitis,
• the late active phase when calcification begins
• quiescent phase
where the synovitis has regressed and the patient may be left without effusion or obvious synovitis but with lose intra-articular calcific and ossific bodies.
The imaging findings vary with these three different phases.
The plain film is the first step in the differentiation from SOC from PVNS.
Small areas of punctate or
occasionally, large conglomerate areas of calcification.
Erosions are significantly less common than in PVNS
consequently the absence of erosions in the presence of calcification is typical.
Difficulties with early disease which is predominantly synovial hyperplasia
Seen in approximately 10% of patients.
In addition early calcification may be obscured by the overlying bone.
CT may be helpful
Rare.
May arise from pre-existing synovial chondromatosis thus symptoms are long standing.
Look for synovial mass
Lobulated margin
Fatty elements on T1
Occasionally phleboliths
Prominent vessels in the vicinity
Recurrent haemarthrosis