Synovial chondromatosis

Synovial chondromatosis is a relative common pathology of the joint. It is also known as synovial osteochondromatosis.

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General

• Benign.
  • Malignant transformation rare <5%.
• Classically location: knee.
  • Hip next most common site.
• Usually adults.
• Prevalence: male > female.

Note:

• This is a clinicoradiologic diagnosis.

Gross/radiology

• Intraarticular calcifications.
• Diffuse involvement of the joint.
• +/-Loose bodies in the joint (AKA joint mice).

Image:

• Synovial chondromatosis (WC).
• SC - gross (rsna.org).

Microscopic

Features:

• Hyaline cartilage +/- lobular surface.
  • +/-Lacunae with binucleate cells.
  • +/-Nuclear atypia - moderate to severe.
• +/-Synovial hyperplasia - ribbon like tissue with an epithelium that has eosinophilic cytoplasm.
• Bone.

DDx:

• Chondrosarcoma.
• Osteoarthritis.

Images

www:

• Synovial chondromatosis (rsna.org).
• Synovial chondromatosis - low mag. (rsna.org).
• Synovial chondromatosis (webpathology.com).
• Loose body with fibrotic synovial membrane (nih.gov).

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LOOSE BODIES, RIGHT ELBOW, REMOVAL:
- FRAGMENTS OF BONE WITH CARTILAGE AND SYNOVIAL TISSUE COMPATIBLE WITH LOOSE BODIES.

TISSUE, CAPSULE LEFT ELBOW, REMOVAL:
- DEGENERATIVE JOINT DISEASE.
- SYNOVIAL HYPERPLASIA WITHOUT SIGNIFICANT INFLAMMATION.
- ROUND BODIES CONSISTING OF BENIGN BONE WITH A FATTY MARROW, AND FIBROUS
  AND CARTILAGINOUS SURFACE, COMPATIBLE WITH LOOSE BODIES.
- NEGATIVE FOR MALIGNANCY.

LOOSE BODY, LEFT KNEE, REMOVAL:
- BENIGN BONE WITH FIBROTIC SYNOVIAL MEMBRANE, CONSISTENT WITH LOOSE BODY.

Micro

The sections show multiple fragments of tissue consisting of bone covered by hyaline cartilage and associated with synovial hyperplasia.

There is no appreciable nuclear atypia or mitotic activity.

See also

• Cartilage.
• Bone.