Histopathology case 1:
- Nodular masses of hyaline cartilage with increased cellularity are covered by a thin fibrous layer and synovial lining.
- Many areas show clustering of nuclei.
- Cytologic atypia is of mild degree only.
- Few nodules show osseous metaplasia on the periphery.
- Myxoid changes are not seen.
Histopathology case 2:
- Nodular masses of hyaline cartilage with increased cellularity are covered by a thin fibrous layer and thin synovial lining.
- Chondrocytes may appear as diffuse patterns and not in the clustering of nuclei.
- Cytologic atypia is of mild degree only.
- Few nodules show osseous metaplasia in the center.
- Myxoid changes are not seen.
Radiology:
- Variable size well-circumscribed multi-lobulated masses involving the joint and present as loose bodies and attached to synovium and adjacent soft tissue. Such appearance may mimic the rice bodies of osteoarthritis. Peripheral calcification can be seen.
- Bone invasion is not seen.
- Joint effusion and erosion may be seen, suggestive of secondary arthropathic changes.
Gross Pathology:
Pearly white to greyish-brownish hyperplastic synovial tissue, with multiple round nodular masses, which are attached to synovium or found as loose marble balls-like structures
Practical Points of Pathoclinics:
- Synovial chondromatosis usually affects a single joint in a middle-old age group. Knee, hip, and elbow joints are commonly involved. Adjacent bursa and soft tissue can be involved.
- The patient usually presents with pain, locking, and swelling of the joint. Loose bodies can be palpated during the examination.
- The cartilage may show nuclear enlargement with mild to moderate nuclear pleomorphism and increased binucleated cells. Few lobules of cartilage can be seen in adjacent soft tissue and appear as an invasion, but such features should not be considered low-grade chondrosarcoma or malignant process. Also, joint involvement and clustering of chondrocytes are not seen in chondrosarcoma.
- Primary synovial chondromatosis is not common, rather, its secondary development after osteoarthritis is much more common. Osteocartilaginous loose bodies of osteoarthritis may become embedded in the synovium, imparting an appearance of synovial chondromatosis. Also, synovial chondromatosis can lead to secondary changes of arthropathy. So definite diagnostic interpretation requires clinical and radiological inputs.
- Synovectomy with the removal of loose bodies is the standard treatment and aims to prevent the development of arthropathy. However, recurrence is common.