Pigmented villonodular synovities in details according to cambell

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Pigmented Villonodular Synovitis (PVNS)

Campbell's Operative Orthopaedics, 15th Ed. (2026) - Chapter 30: Synovial Lesions

Overview / Classification

PVNS is a benign but locally aggressive synovial proliferative disorder that occurs in two distinct forms:

Form	Also Known As	Key Feature
Localized	Focal nodular synovitis	Solitary pedunculated lesion
Diffuse	Classic PVNS	Involves entire synovium of the affected joint

It is closely related to Giant Cell Tumor of Tendon Sheath (GCTTS) - the localized form is histologically identical to GCTTS; the diffuse form is also histologically identical but involves the entire joint synovium. Both are now increasingly classified under the umbrella term Tenosynovial Giant Cell Tumor (TSGCT).

Epidemiology & Clinical Presentation

Typically presents with monoarticular pain and swelling
Most common joint: Knee (by far the most frequent)
Other joints affected: Hip, ankle, shoulder, wrist, and others
Intraarticular lesions may cause mechanical symptoms (locking, clicking)
A palpable mass may be present
Symptoms are often nonspecific, leading to delayed diagnosis
Joint aspiration characteristically reveals serosanguineous or blood-tinged fluid - a hallmark finding

Imaging

Plain Radiographs:

Often normal in early or soft-tissue disease
May show bony erosions, especially when the hip is involved
No soft-tissue abnormality may be visible on plain films (see Figure 30.14 A & B below)

MRI - The Key Diagnostic Tool:

Shows intraarticular masses that are dark on BOTH T1-weighted and T2-weighted sequences - this is the classic and virtually diagnostic MRI finding
The hemosiderin deposition (from repeated hemorrhage into the joint) causes low signal on both T1 and T2 due to its paramagnetic properties
MRI also delineates the full extent of the disease process

Figure 30.14 from Campbell's - Plain radiographs (A, B), T1-weighted sagittal MRI (C), T2-weighted axial MRI (D), and intraoperative photograph (E) of PVNS of the knee:

Figure 30.14 - PVNS of the knee: Plain radiographs (A, B) show no soft-tissue abnormality; T1-weighted (C) and T2-weighted (D) MRI demonstrate a diffuse intraarticular dark process; intraoperative view (E) shows diffuse PVNS

A & B: Plain radiographs show no soft-tissue abnormality. C: T1-weighted (sagittal) MRI - diffuse dark intraarticular process. D: T2-weighted (axial) MRI - also dark (hemosiderin). E: Intraoperative view of diffuse PVNS of the knee.

Histology

Localized form (Focal Nodular Synovitis):

Solitary pedunculated lesion
Histologically identical to Giant Cell Tumor of Tendon Sheath

Diffuse form:

Also histologically identical to the localized form
The distinction is that it involves the entire synovium of the affected joint

Microscopic features (Figure 30.13):

Bland polyhedral (histiocyte-like) cells surrounded by collagen
Giant cells (multinucleated)
Hemosiderin deposits (the "pigmented" component, responsible for brown-yellow appearance)
Foam cells (lipid-laden histiocytes)
Low mitotic activity

Figure 30.13 - PVNS histology (H&E ×20): Bland polyhedral cells surrounded by collagen; giant cells and hemosiderin are present

H&E ×20: Bland polyhedral cells with collagen stroma, multinucleated giant cells, and scattered hemosiderin deposits (brown granules).

Treatment

The three goals of treatment are:

Alleviation of symptoms
Minimizing recurrence
Preservation of the joint

Localized Form

Marginal excision is the recommended treatment
Can frequently be treated by arthroscopic excision
Reported recurrence rate with arthroscopic excision: 0% to 8%

Diffuse Form

Total synovectomy is the recommended treatment (open or arthroscopic)
Higher recurrence rates than the localized form
Radiotherapy may be justified if surgery fails to control the disease process

Advanced / Refractory Disease

If significant secondary degenerative changes of the joint surfaces have occurred, arthroplasty should be strongly considered
Clinical trials are currently underway evaluating a potential role for CSF1R inhibitors (Colony Stimulating Factor 1 Receptor - targets the CSF1/CSF1R signaling pathway which drives synovial proliferation; pexidartinib is the approved CSF1R inhibitor)

Relationship to Adjacent Lesions (Campbell's Context)

Campbell's places PVNS within the Synovial Lesions chapter alongside:

Lesion	Key Distinguishing Feature
Synovial chondromatosis	Cartilaginous metaplasia; multiple loose bodies; radiographically visible calcified loose bodies
Giant cell tumor of tendon sheath	Fingers/tendon sheaths; localized; histologically same as PVNS
PVNS	Joint synovium; hemosiderin; dark on T1 and T2 MRI

Summary Table

Feature	Detail
Nature	Benign synovial proliferative lesion
Forms	Localized (focal) vs. Diffuse
Most common joint	Knee; also hip, ankle, shoulder, wrist
Symptom	Monoarticular pain, swelling, mechanical symptoms
Joint fluid	Serosanguineous / blood-tinged
X-ray	Often normal; bony erosion (especially hip)
MRI hallmark	Dark on BOTH T1 and T2 (hemosiderin)
Histology	Bland polyhedral cells, giant cells, hemosiderin, foam cells
Localized Rx	Marginal/arthroscopic excision (recurrence 0-8%)
Diffuse Rx	Total synovectomy ± radiotherapy if refractory
End-stage joint	Arthroplasty
Emerging therapy	CSF1R inhibitors (e.g., pexidartinib)

Source: Campbell's Operative Orthopaedics, 15th Edition (2026), Chapter 30 - Soft Tissue Tumors, Synovial Lesions section, pp. 1264-1268.

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