Giant cell tumor of tendon sheath (Pigmented Villonodular tenosynovitis)

  • second most common tumor of the hand after ganglion
  • Not necessarily related to tendon sheaths and not uniformly associated with giant cells
  • often more firm than ganglia and are not visible by transillumination.

Classification

  1. localized
  2. diffuse – affects lower extremitiesmost commonly found around the knee, followed by the ankle and foot

Epidemiology

  • Peak 30-50 years old - 50% younger than 40 years
  • F>M; 3:2
  • associated with degenerative joint disease, especially in the distal interphalangeal (DIP) joint dorsally

Aetiology

  • Unknown
  • Theories include trauma, disturbed lipid metabolism, osteoclastic proliferation, infection, vascular disturbances, immune mechanisms, inflammation, neoplasia, and metabolic disturbances
  • most widely accepted theory, as Jaffe et al proposed, is that of a reactive or regenerative hyperplasia associated with an inflammatory process.

Histopathology

  • Grossly, digit tumors tend to be small, multiple, surrounded by a thin fibrous capsule, and had a variegated appearance, while the large joint tumors were relatively large and covered by one or more layers of synovium.
  • On cut sections, these tumors have a mottled appearance, varying in color from grayish brown to yellow-orange. The coloration depends on the amount of hemosiderin, collagen, and histiocytes in the sample. Tumors with more hemosiderin deposition due to bleeding have more of the yellow-orange or even reddish brown color
  • mature collagen capsule often surrounds tumor, continuous with fibrous septae within the substance of the tumor that divide it into vague nodules (no capsule in diffuse form)
  • moderately cellular and composed of sheets of rounded or polygonal cells that blend with hypocellular collagenized zones.
  • variable numbers of giant cells are present
  • Hemosiderin-containing xanthoma cells are common and often localized at the periphery of the lesion

Cytology

  • The histological characteristics of the solitary nodular, multiple nodular, and diffuse lesions suggested that they have a common histogenesis that is characterized by proliferation of fibroblastic or histiocytic mesenchymal cells, or both, beneath the synovial or tenosynovial lining cells, and by collagen production.
  • Foam cells and iron deposits appear to be secondary changes and are usually seen in the periphery of the expanding nodules.
  • Predominant cell type is mononuclear cell – 2 most likely origins are synovial cell or monocytic macrophage system origin (some resemblance to osteoclasts)
  • Controversial as to whether this is a true neoplasm or a nonneoplastic lesion – evidence suggests cells are polyclonal.
  • Mitotic and apoptotic figures are a common feature and do not indicate clinical behaviour

Clinical

  • Occurs volar surface of hand (2/3rds), radial 3 digits and DIPJ
  • Firm, nodular and non tender, fixed to underlying structures
  • Skin is free over proximal tumors but fixed to distal structures
  • Perform a digital Allens test
  • Does not transilluminate unlike ganglions
  • Grows slowly
  • Sensory deficit may be present if close to digital nerve
  • Malignant transformation not reported but a malignant form of GCT has been well described

Differential diagnosis

  1. ganglion cyst
  2. foreign body granuloma,
  3. necrobiotic granuloma,
  4. tendinous xanthoma,
  5. fibroma of the tendon sheath
  6. infection
  7. rheumatoid nodule
  8. epidermoid cyst
  9. lipoma
  10. knuckle pad

Investigation

  • Xray
  • benign-appearing circumscribed soft-tissue shadow in 50%
  • intralesional calcification - can be confused with synovial chondromatosis, periosteal chondroma, or calcific tendonitis
  • pressure erosion of bone (20%) - more common in the feet because the strong ligaments in this region frequently prevent outward tumor growth
  • MRI
  • decreased signal intensity on T1 and T2; enhances with gadolinium
  • degree to which these low-signal-intensity areas are present depends on the amount of hemosiderin, which varies. PVNS often has more low-signal-intensity areas on T2-weighted images, secondary to its higher hemosiderin content resulting from its characteristic intralesional bleeding.
  • Bone invasion seen in diffuse type is rare in localized forms

Treatment

  • Marginal excision – recurrence rate 20-50% due to satellite lesions. Risk may be reduced by postop radiotherapy (4% recurrence in 1 study - J Bone Joint Surg Br. 2000 May)
  • If the tumor appears to be arising from the joint, it is important to perform a capsulotomy to inspect the joint and to debride any pigmented tissue remaining within the joint.
  • Arthrodesis if extensive joint involvement or degenerative changes seen
  • Risk factors for recurrence :
  • the presence of adjacent degenerative joint disease
  • an injury at the DIP joint of the finger or the IP joint of the thumb
  • radiographic presence of osseous pressure erosions.