A locally aggressive synovial tumour which affects both large joints & tendon sheaths
Same entity as giant cell tumour of tendon sheath
Terminology
Other names for this disorder have included
synovial xanthoma
synovial fibroendothelioma
synovial endothelioma
benign fibrous histiocytoma
xanthomatous giant cell tumour
myeloplaxoma
chronic haemorrhagic villous synovitis
Epidemiology
1.8 per million
No sex or racial predilection
Most common in the 20s & 30s
Aetiology
Essentially unknown
Theories
Hirohata
localized disturbance in the metabulism of lipids
Trauma.
However, low incidence in patients with haemorrhagic disorders, & has not been consistently reproduced in experimental animals
Inflammation
Widest held theory since 1941 (Jaffe)
Trigger for inflammation has not been identified
Pathology
Gross
Tan colour
In the knee usually consists of multiple nodules, often with dramatic associated hyperplastic villous changes in the synovium, giving a straggly beard appearance
Much more frequently found as a sulitary nodule & more rarely as a diffuse multinodular condition
Most common sites are the knees & fingers
Can also occur in the wrist, hip, ankle & toes
Usually painless or only mildly painful. Onset is insidious
Approximately 50% can recall an episode of trauma
Signs
Local warmth
Swelling
Stiffness
Palpable mass
Point tenderness in 50%
Investigations
Aspiration
produces a deep xanthochromic to brownish stained bloody fluid
Xray
Fingers
usually only soft tissue swelling or there may be cortical erosion
Knee
major finding is soft tissue swelling which may be massive
Erosion may cause a lytic intramedullary lesion. Erosion is rare in the knee because a substantial bulk of tumour can be accommodated, but is more common in the hip
Lucencies on either side of a joint are very characteristic of PVNS
Findings of extension outside the joint, calcification or cortical destruction suggest the diagnosis of synovial sarcoma
MRI
low to intermediate signal intensity on T1 & T2 weighted images
Treatment
Excision
Options
arthroscopic
open using anterior & posterior approaches
In the posterior approach, a lazy S incision is made, the gastrocnemius heads are released & the capsule opened using two T shaped incisions, one medial & one lateral
menisci are detached both anteriorly & posteriorly & are later repaired
Radiation synovectomy
Radioculloid yttrium-90 is injected into the knee
Doesn’t appear to affect the knee cartilage
External beam irradiation
may be used. One dosage that has been used is 35Gy
Tends to be used in recurrences
Arthrodesis
End stage destruction, particularly in the ankle, often requires arthrodesis
Prognosis
Metastatic disease may develop
MRI is effective in detecting recurrence postoperatively
Recurrence is common in the diffuse form of the disease
E.g. 33% in a series of 18 patients with PVNS of the knee
