Pigmented Villonodular Synovitis
Pigmented Villonodular Synovitis is the most common disorder of synovium
The primary factor is mitochondrial dysfunction
Origin is controversy:
- Reactive: Evidence of trauma, multifocal origin
- Neoplastic: Autonomous growth, apoptosis resistance
Classification
Pigmented Villonodular Synovitis | Localized | Diffused |
---|---|---|
1. Localized | ||
Identical to GCT of the tendon sheath | History is similar to GCT but involves the whole synovium | |
Age | 30-50 Years | Younger age |
Female> Male | Female> Male | |
Mostly affected: hand (adjacent to IP joint) | Mostly affected is the Knee | |
Clinical Features | Non-tender, firm, irregular nodules of varying size fixed to underlying structures: free from skin | The long history of pain in joints, swelling disproportionately to the degree of pain, locking, hemarthrosis |
Gross | 0.5 – 4 cm lobulated mass Pink gray background with yellow-brown areas | Absence of collagen capsule |
Microscopic | Polyhedral cells surrounded by collagen, ain’t cells, xanthomas, mitotic figures, hemosiderin deposition | Polyhedral cells surrounded by collagen, ain’t cells, xanthomas, mitotic figures, hemosiderin deposition |
On Aspiration: Serosanguinous fluid or blood-tinged fluid | ||
X-Rays | Circumscribed soft tissue mass, cortical erosion in some cases | Intraarticular effusion, lobulated mass Invade subchondral bone- Cyst formation |
Apple core deformity:- Concentric erosion of femoral neck Marginal erosion: bubbly appearance | ||
MRI | Most informative: Blooming artifact from hemosiderin |
Treatment Options
Marginal excision
Synovectomy
- Total
- Open
- Arthroscopic
Arthroplasty
Newer advances:
- Intraarticular radiation synovectomy
- TNF-α blockage therapy in resistance cases
Synovial Sarcomas
Is a misnomer ( Because malignancy is rare in joints and with no histochemical relation to CK-negative normal synovium
Rare and aggressive
Near joints (Typically in the knee and ankle joints)
Age: around 30 years
Male: Female:: 1.2:1
Etiology
Unknown
Chromosomal translocation that fuses SYT gene from Chromosome 18 either SSX1 or SSX2
{SYT-> SSX1 / SYT-> SSX2 } protooncogenes
Clinical features
Swelling + Pain/ tenderness
Limping or difficulty using legs, arms, hands, and feets
Pathological Examinations
Gross:
Well circumscribed, firm, and grayish pink + Calcification
Microscopic :
Biphasic: Epithelial + Sarcomatous components (Spindle shaped with fibroblast)
Hyalinization
Monophasic: Only one of the above two (mostly spindle-shaped ) misdiagnosed with fibrosarcomas
Stains
Secretions within epithelial cells:
PAS +ve
Diastase – Resistance
Alcian Blue +ve
Mucicarmine +ve
Reticulin stain (Plumps of rounded cells) – Biphasic pattern of tumor
Epithelial markers: Cytoketatin +ve
- 7 and 19 only positive in synovial sarcomas
- 8 and 18 positive in synovial sarcomas and others as well
Secretions within spindle cells:
PAS -ve
Alcian blue +ve
Mesenchymal markers: Vimentin +ve
EMA +ve
S100 +ve
CD 99 +ve
Scl-2 +ve
Associated with chromosomal translocation t (x;18), p911.2;q11.2)
Treatment Options
Surgery + Radiation + Chemotherapy
Complete surgical excision + Muscles + Lymph nodes
See also: Limb Salvage Surgery: Principles