[Additional comments on the differential diagnosis of rare bone diseases (author's transl)].

We report about two seldom types of diseases of bones. Both came to our hospital with the diagnosis Osteomyelitis. The first case, the Mafucci-Syndrome, is presented--a systemic Chondrodysplasia with Angiomatosis. This disease is not hereditary. There are found multiple Enchondromas mostly in the longer bones. In 20% the cases of the Mafucci-Syndrome get malignant. The second case shows the Conradi-Hünermann-Syndrome a Chondrodysplasia calcificans congenita, which seems to be hereditary. The characteristic sign is the minor growth of the bones, caused by early deposition of lime in the regions of ossification. Malignity is not described.