Synovial chondrosarcoma: a single‐institution experience with molecular investigations and review of the literature

Aims the aim is to evaluate the available diagnostic histologic criteria of synovial chondrosarcoma and to screen for the presence of IDH1/2 mutations in a series of cases of this malignant cartilaginous neoplasm. Methods and results ten cases of synovial chondrosarcoma diagnosed at our Institute were reviewed. At presentation, all tumors occurred in adults (median age 62 years). The most common location was the knee joint (5 cases) and the size at diagnosis ranged from 3 to 17 cm. Eight patients had secondary synovial chondrosarcomas associated with pre-existing/recurrent or concomitant synovial chondromatosis. Five patients had local recurrences and three had lung metastases. All cases with intralesional excisions developed local recurrences while those that underwent wide resections did not. At last follow-up (mean: 91 months), available for nine patients, seven patients were alive and disease free, one patient died of disease and one was alive with paravertebral metastases. Frequent histological features observed included loss of clustering of chondrocytes (9 cases), presence of variable amount of myxoid matrix (8 cases), peripheral hypercellularity (8 cases), tumor necrosis (6 cases) and spindling of chondrocytes (4 cases). Of the seven cases amenable for evaluation of bone permeation, six showed infiltration of bone marrow. All seven cases screened for mutations of the exon 4 of IDH1 and IDH2 were found to be wild-type. Conclusions Histologic criteria in correlation with clinical and radiological features allow recognition of synovial chondrosarcoma. IDH1/2 mutations were not present in synovial chondrosarcoma. Adequate surgical margins are important for disease control.