A case of synovial chondromatosis of the knee joint

―Feasibility of synovial fluid cytology for preoperative diagnosis―

Abstract

Background : Synovial chondromatosis is a cartilaginous neoplasm of the synovial membrane and usually diagnosed based on clinical and radiological findings. We report herein on a case of synovial chondromatosis diagnosed based on the synovial fluid cytology, which was thought to be feasible for preoperative diagnosis.

Case : A 34-year-old woman visited our hospital because of pain and swelling of the left knee from one year previously. Radiological examination showed increased synovial fluid, but no obvious findings of underlying disease. Synovial fluid cytology was performed and the smear revealed nodular clusters of chondrocytes surrounded with a chondroid matrix. The cells showed mild nuclear atypia such as anisonucleosis, binucleation, small nucleoli and high cellularity. The arthroscopic findings revealed whitish synovial tissues and a synovectomy was performed. Histological examination showed primary synovial chondromatosis.

Conclusion : Synovial fluid cytology is useful for preoperative diagnosis of synovial chondromatosis, when diagnosis based on radiologic examination is difficult.