Bone Tumors - A Challenge for Cooperation E. GRUNDMANN Among the wide variety of human tumors, those of the skeletal system have an exceptional position in several respects. Above all, they are comparatively rare, and that is why reliable diagnostic criteria were compiled only recently, that is during the last three decades. It is only five years since the outlines of an international code of classi­ fication were traced. The code was applied and discussed critically and with varying results by several international working groups. Cer­ tain drawbacks are due to the broad and manifold spectrum of histolo­ gic manifestations in neoplastic bone. Even the best experts in dia­ gnostic histology would hardly be able to classify more than 85% of all bone tumors after the proposed code system. For quite a long time the osteoclastic giant cells, observed in almost any kind of bone tumor, have so much fascinated the histologist's eye that he was apt to pro­ claim the diagnosis "brown giant cell tumor" for almost any osteoclas­ tic tumor regardless of its benignity or malignancy. Nowadays the group of "giant cell tumors" though'restricted, still remains disputed in terms of malignancy and benignity. The problem will certainly not be settled in a definite way without extensive follow-up studies. In this context we may see actual progress in new regional. bone tumor registries being set up after the American example in many countries, among them the German Federal Republic.

Bone Tumors - A Challenge for Cooperation..- I. Experimental Tumors.- Comparative Pathology of Bone Tumors in Animals, with Particular Emphasis on the Dog.- Bone Tumors Induced by Inhalation of 238PuO2 in Dogs.- Experimental Induction of Bone Tumors by Short-Lived Bone-Seeking Radionuclides.- II. Pathogenesis.- Etiology of Childhood Bone Cancer: Epidemiologic Observations.- The Endogenous Origin and Transmission of RNA Viral Genomes that Code for Cancer.- Pathogenesis of Radiation and Virus-Induced Bone Tumors.- III. Pathology.- The WHO Classification of Bone Tumors.- Primary Malignancy, Secondary Malignancy and Semimalignancy of Bone Tumors.- Common Errors Made by Pathologists in the Diagnosis of Bone Tumors.- Aspiration (Puncture or Needle) Biopsy in Bone Lesions.- Cytologic and Cytochemical Behavior of Primary Malignant Bone Tumors.- Histochemical and Electron-Microscopic Aspects of Bone Tumor Diagnosis.- IV. Immunology.- Morphological, Biological, Immunological and Biochemical Studies on Bone Tumors of Animals and Man.- Immunologic Aspects of Human Sarcomas.- The Immune-Status in Patients with Bone and Soft-Tissue Sarcomas.- Laboratory Models of Minimal Residual Cancer: Development and Preliminary Immunotherapy Studies.- V. Therapy.- The Treatment of Malignant Bone Tumors by Conservative Surgery.- Management of Osteogenic Sarcoma at the Mayo Clinic.- Surgical Treatment of Solitary Bone Cysts.- Resection of Malignant Bone Tumors.- Giant-Cell Tumors and Chondrosarcomas: Grading, Treatment and Results (Studies of 209 and 131 Cases).- X-Ray Therapy of Primary Bone Tumors.