Primary Synovial Chondromatosis of the Ankle in a Child: A Rare Case Presentation and Review of Literature

INTRODUCTION: Synovial chondromatosis is not a common condition and involvement of the ankle joint is quite rare. We found only one case of synovial chondromatosis of the ankle joint among the pediatric population. We present a case of a 9-year-old boy with synovial chondromatosis of the left ankle. CASE REPORT: A 9-year-old boy had synovial osteochondromatosis in the left ankle joint, which caused pain, swelling, and restriction of movement of the left ankle. Radiological examinations showed variable size calcific foci adjacent to the medial malleolus and medial ankle joint space with mild soft-tissue swelling. The ankle mortise space was well-maintained. The magnetic resonance imaging of the ankle joint revealed a benign synovial neoplastic process and a few focal marrows containing loose bodies. The synovium was thick, and there was no articular erosion. The patient was planned and underwent an en bloc resection. A lobulated pearly white mass arising from the ankle joint was observed intraoperatively. Histological examination also showed attenuated synovium with osteocartilaginous nodule with binucleated and multinucleated forms of chondrocyte typical of osteochondroma were appreciated. Endochondral ossification, mature bony trabeculae with intervening fibro adipose tissue, was noted. The patient had remarkable relief of clinical complaints and was almost asymptomatic at the time of the first follow-up. CONCLUSION: Synovial chondromatosis may present with diverse clinical manifestations according to the different stages of the disease as described by Milgram; like joint pain, limitation of movements, swelling due to the close proximity of important structures including joints, tendons, and neurovascular bundles. A simple radiograph with a characteristic appearance is usually sufficient in confirming the diagnosis. In pediatric patients, overlooking these conditions may result in growth abnormality, skeletal deformities, and several mechanical problems. We suggest that when dealing with the case of swelling in or around the ankle, the differential diagnosis should include synovial chondromatosis.