hardcastle syndrome hardcastle syndrome hardcastle syndrome is a rare genetic disorder on chromosome 9 at 9p22-p21. it affects the long bones. there is a high risk for histiocytoma. hardcastle syndromeother namesbone dysplasia-medullary fibrosarcoma syndrome, diaphyseal medullary stenosis-malignant fibrous histiocytoma syndromehardcastle syndrome is inherited in an autosomal dominant pattern.