In this paper three families are reported with members who had
hereditary bone dysplasia that was originally described by Arnold in one
family. We provide further information about that family and suggest that
the diagnosis of the malignant change should be changed from fibrosarcoma
to malignant fibrous histiocytoma. A thorough search of the literature has
failed to reveal any conditions, either hereditary or acquired, that are
similar. The major feature of the dysplasia is diaphyseal medullary
stenosis of bone with overlying cortical-bone thickening, and the
propensity to malignant transformation and fractures with minimum trauma is
emphasized. The tumors in seven, and possibly eight, of the nine patients
in whom a malignant lesion developed were originally classified as
fibrosarcoma and proved to be markedly aggressive. The hereditary pattern
appears to be autosomal dominant. The clinical manifestations of a
malignant lesion occur generally in the second to the fifth decades of
life.