Giant extra-articular synovial osteochondromatosis of the left proximal thigh: A case report

Secondary extra-articular synovial osteochondromatosis with involvement of the leg, ankle and foot. An exceptional case

Extraarticular synovial osteochondromatosis is a very rare benign disease whose aetiology may be primary or secondary to pre-existing pathology or after trauma. The diagnosis can be made with plain radiography and CT, and MRI is necessary to evaluate the non-mineralized soft tissue component and assess extension. It must be confirmed with a pathological study by biopsy or resection. There is up to a 5% chance of malignant transformation. The treatment of choice for the extensive extra-articular form is surgery by open resection. The case presented illustrates an atypical form of secondary extraarticular OCS with multiple involvement of the leg, ankle and foot.

Giant Extra-Articular Synovial Chondromatosis of the Ankle Joint - A Rare Case Report

INTRODUCTION

Synovial chondromatosis (SC) commonly involves large joints such as the knee and hip with smaller joints being less frequently involved. Extra-articular involvement is very rare, and here, we are presenting the first case of giant extra-articular SC originating from the ankle joint.

CASE REPORT

A 42-year-old male presented to the outpatient department with painless swelling over the lateral malleolus for 2 years. Diagnostic imaging suggested the involvement of the synovial lining with the swelling. The mass was excised and histopathology proved the diagnosis of SC.

CONCLUSION

Extra-articular involvement in SC has been mainly reported in the synovial sheath or bursae of the hand and foot, but they can involve ankle joint also. In recent times, there have been concerns about potential malignant transformation of these lesion to chondrosarcoma, diagnosing these lesions have become important.

Secondary Extra-Articular Synovial Osteochondromatosis with Involvement of the Leg, Ankle and Foot. An Exceptional Case

Extraarticular synovial osteochondromatosis is a very rare benign disease whose aetiology may be primary or secondary to pre-existing pathology or after trauma. The diagnosis can be made with plain radiography and CT, and MRI is necessary to evaluate the non-mineralized soft tissue component and assess extension. It must be confirmed with a pathological study by biopsy or resection. There is up to a 5% chance of malignant transformation. The treatment of choice for the extensive extra-articular form is surgery by open resection. The case presented illustrates an atypical form of secondary extraarticular OCS with multiple involvement of the leg, ankle and foot.