The one case in which an osteoclast-rich component was not detected despite extensive sampling was sited in the diaphyseal region and presented in a patient with Hardcastle syndrome, characterized by diaphyseal medullary stenosis (sclerosis) with bone malignancy (malignant fibrous histiocytoma), a germline disorder revealing structural alterations in the gene encoding methylthioadenosine phosphorylase.25 Here, MTAP is linked to histiocytoma.