Synovial Chondromatosis and Chondrosarcoma: A Diagnostic Dilemma

Brita L Sperling,Vance Chow,Steven Angel,Grant Stoneham,Andrew Mcfadden,Rajni Chibbar

doi:10.1080/13577140310001607293

Abstract

Purpose: The progression of synovial chondromatosis to chondrosarcoma is very rare. Distinction between these two entities may be difficult on histology alone, and should be based on clinical, radiographic and microscopic evidence. Immunohistochemical markers that would facilitate differentiation between synovial chondromatosis and chondrosarcoma are currently being investigated. Patients: We describe the cases of two patients who presented with synovial chondromatosis and progression to synovial chondrosarcoma during periods of 7 and 11 years. Several biopsies and resected specimens demonstrated synovial chondromatosis before a diagnosis of chondrosarcoma was made. Method: We have examined five markers (Bcl2, Ki67, p27, p16, and p53) in all specimens from these cases, as well as known cases of chondromatosis and chondrosarcoma for control purposes. Results: We found increased expression of Bcl2 in benign chondromatosis compared to synovial or central chondrosarcomas. Discussion: Distinction between chondromatosis and its progression to low grade chondrosarcoma is difficult at histological level, and must involve incorporation of clinical and radiographical data. Although preliminary, our study suggests that reduced or absent expression of Bcl2 is associated withmalignant transformation of chondromatosis.

Highlights

Synovial chondromatosis, known as synovial osteochondromatosis or synovial chondrometaplasia, is an idiopathic synovial proliferation
There were scattered binucleated cells and there was mild focal atypia of chondrocytes characterized by slight nuclear enlargement and hyperchromasia, suggestive of probable early low grade chondrosarcoma
It is difficult to diagnose low grade chondrosarcoma arising in chondromatosis on histology alone, as they overlap in cyto-architectural features

Summary

Introduction

Known as synovial osteochondromatosis or synovial chondrometaplasia, is an idiopathic synovial proliferation. It is characterized by multiple nodules of metaplastic hyaline cartilage within the synovial membrane of a joint, often detaching to form intra-articular loose bodies.[1] Synovial chondrosarcoma is an uncommon malignant cartilaginous neoplasm arising in synovial tissue, with only 34 reported cases in the literature to date.[2] Most show evidence of concurrent and most likely pre-existing primary synovial chondromatosis, suggesting malignant transformation.[1]. Documented malignant transformation of synovial chondromatosis to chondrosarcoma is quite rare, with approximately 20 cases reported in the literature to date. The risk of progression to malignancy is reportedly as high as 5%.3

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Conclusion