As a routine immunohistochemical marker, YKL-40 is not optimal, because it is too widespread, but it may be of value in the postoperative follow-up of patients with potentially malignant chondroid tumors, and in the monitoring of patients with multiple osteochondromas or enchondromas, who have an increased risk of developing chondrosarcomas. This evidence concerns the gene CHI3L1 and Multiple osteochondromas.