Synovial chondromatosis

SYNOVIAL CHONDROMATOSIS

• Definition : It is a benign condition characterised by metaplastic nodular cartilaginous proliferation under the synovial surface in bursae, tendons and joints

• Synonyms –synovial osteochondromatosis, Synovial chondroma

• Studies have suggested that this condition is in between enchondroma and chondrosarcoma

• Clinical features :

  • Most common symptoms is pain followed by swelling

  • Duration is variable

  • Age – common in young adults

  • Sex – Slight male predominance

  • Sites –

    • It is monoarticular (usually), involving knee (common site) followed by hip joint

    • Unusual sites –

      • Temporomandibular joint

      • Soft tissues around joints and bursae

      • Facet joints of vertebrae

• Radiographic findings:

  • Swelling of soft tissue of synovium

  • Some cases – radio opaque masses in joint

• Gross findings:

  • Synovial membrane is thickened and has numerous nodules of cartilage each measuring less than 1mm to several centimeters in diameter giving it “ cobble stone” appearance

  • Nodules of cartilage may break of and present in joint as loose bodies

• Microscopic findings:

  • Synovial tissue lined by flattened synovial cells

  • Underneath tissue shows nodules with clusters of chondrocytes separated by active cartilage matrix

  • Chondrocytes show hyperchromasia and nuclear enlargement

  • Double nucleated cells may be present

  • Calcification may occurs as large masses or as powdery deposits between chondrocytes

  • Enchondroid calcification may also occur

• Differential diagnosis:

  • Chondrosarcoma:

    • It involves synovium and gives the appearance similar to synovial chondromatosis

    • Unlike clustering, chondrosarcoma has sheets like arrangement of chondrocytes

  • Osteocartilagenous loose bodies secondary to degenerative joint diseases

    • In loose body the cartilage in hypocellar and has layering effect (central nodes of cartilage that seems to grow by the addition of concentric layers)

    • Chondrocytes lack neoplastic appearance as seen in synovial chondromatosis

• Treatment and prognosis

• • Surgical removal

  • Recurrence may occur in the joint and erode into bone

  • Malignancy is uncommon

Reference:

1. Krishnan unni,carrie Y.Inwards,Jimlia A. Bridge lars-Gunnar Kindblom,lester E.Wold. Synovial chondromatosis. In synovial tumors: Tumors of the bones and joints. AFIP atlas of tumor pathology.Series 4.386-388.

2. Peter A.Kumphrey. Joints and synovinum. In: Peter A.Humphrey, Louis P.Dehner, John D.Pfei The Washington Manual of Surgical Pathology. second edition.2016.822-827.