May 30, 2024

Pigmented Villonodular Synovitis

Pigmented Villonodular Synovitis is the most common disorder of synovium

The primary factor is mitochondrial dysfunction

Origin is controversy:

  1. Reactive: Evidence of trauma, multifocal origin
  2. Neoplastic: Autonomous growth, apoptosis resistance
Pigmented Villonodular Synovitis


Pigmented Villonodular SynovitisLocalizedDiffused
1. Localized
Identical to GCT of the tendon sheathHistory is similar to GCT but involves the whole synovium
Age30-50 YearsYounger age
Female> MaleFemale> Male
Mostly affected: hand (adjacent to IP joint)Mostly affected is the Knee
Clinical FeaturesNon-tender, firm, irregular nodules of varying size fixed to underlying structures: free from skinThe long history of pain in joints, swelling disproportionately to the degree of pain, locking, hemarthrosis
Gross0.5 – 4 cm lobulated mass
Pink gray background with yellow-brown areas
Absence of collagen capsule
MicroscopicPolyhedral cells surrounded by collagen, ain’t cells, xanthomas, mitotic figures, hemosiderin depositionPolyhedral cells surrounded by collagen, ain’t cells, xanthomas, mitotic figures, hemosiderin deposition
On Aspiration: Serosanguinous fluid or blood-tinged fluid
X-RaysCircumscribed soft tissue mass, cortical erosion in some casesIntraarticular effusion, lobulated mass
Invade subchondral bone- Cyst formation
Apple core deformity:- Concentric erosion of femoral neck
Marginal erosion: bubbly appearance
MRIMost informative: Blooming artifact from hemosiderin
Apple core deformity
Apple core deformity

Treatment Options

Marginal excision


  • Total
  • Open
  • Arthroscopic


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



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


Well circumscribed, firm, and grayish pink + Calcification

Microscopic :

Biphasic: Epithelial + Sarcomatous components (Spindle shaped with fibroblast)


Monophasic: Only one of the above two (mostly spindle-shaped ) misdiagnosed with fibrosarcomas


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