Diaphyseal aclasis is ?

Ans. is 'a' i.e., Multiple exostosis Hereditary multiple exostoses The ordinary osteochondroma is single; but in the condition known as Diaphysial aclasis (multiple exostosis) the tumor affect several or many bones. Hereditary multiple exostoses is an autosomal dominant hereditary disorder. The risk of malignant changes to a chondrosarcoma is higher in these multiple lesions than in the solitary lesion. Metaphysis of long bones is affected, however, skull and pelvis may also be affected. Multiple exostoses can lead to shoening and bowing of bones; affected individuals often have a sho stature.