Joint tumors
Synovial chondromatosis

Topic Completed: 1 June 2013

Minor changes: 30 September 2019

Copyright: 2002-2019,, Inc.

PubMed Search: Synovial chondromatosis [title] joints "loattrfree full text"[sb]"

Vijay Shankar, M.D.
Page views in 2019: 8,656
Page views in 2020 to date: 3,005
Cite this page: Shankar V. Synovial chondromatosis. website. Accessed May 24th, 2020.
Definition / general
  • Also called synovial chondrometaplasia, synovial osteochondromatosis
  • Mean age 41 years, range 17 - 64 years, 2/3 male (Hum Pathol 1998;29:683)
  • Primary disease is uncommon, unknown etiology, aggressive (Hum Pathol 1979;10:439)
  • Usually monoarticular, can be bilateral rarely (JCDR 2012;6:475), affecting knee, hip, elbow and communicating bursae; may affect adjacent soft tissue
  • Aggravated by infection and trauma
  • May be extra-articular (tenosynovial chondromatosis)
Secondary disease
  • Associated with degenerative joint disease - growth of fragments of articular cartilage
  • Initially intrasynovial disease without loose bodies; then intrasynovial proliferation and free loose bodies, then multiple free osteochondral bodies without intrasynovial disease
  • No atypia
Radiology description
  • Xray: usually calcific densities within joint; may be negative or show diffuse joint swelling
Case reports
  • Excision but frequently recurs; 5% become malignant
Clinical images

Images hosted on other servers:

Smooth white nodule

Showing extent of disease

Gross description
  • Numerous round osteocartilaginous nodules cover a thickened synovial surface or float freely within joint space
Microscopic (histologic) description
  • Cartilage cells with variable atypia or binucleated forms within synovium; clusters of chondrocytes are often arranged in lobules; no underlying arthritis
Microscopic (histologic) images

Images hosted on other servers:

Metaplastic cartilage in synovium

Clusters of chondrocytes

Resembles Grade 1 chondrosarcoma

Nodule of cartilage

Loose bodies

Subsynovial cartilaginous nodule

Moderate atypia of chondrocytes

Osteochondral loose body

Cartilaginous tissue enclosed by synovial tissue

Differential diagnosis
  • Cartilaginous loose bodies: more common but associated with arthritis
  • Chondrosarcoma: not within a joint, no characteristic clustering pattern, marked myxoid change, spindling of nuclei
  • Injury related soft tissue calcification
  • Lipoma arborescens with osseous metaplasia
  • Neuropathic arthropathy or osteochondritis dissecans: no lobulation, clustering or atypia
  • Pigmented villonodular synovitis
  • Secondary synovial chondrometaplasia due to degenerative joint disease
  • Synovial vascular malformation
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