[Diagnosis of bone tumors]

The correct diagnosis of bone tumors involves considerable methodological efforts. Because of the rarity of primary bone tumors Uehlinger initiated a centralisation in the form of bone tumor registries. A sufficient number of these registries exist in the German-speaking countries (for example, Münster, Madgeburg, Giessen, Freiburg, Basel, Wien). Our experience with the organisation of interdisciplinary collaboration, methodology and the value of special examination techniques (immunohistochemistry, DNA analysis, cytogenetics) are reported. Since 1975, 7,576 primary bone tumors have been recorded in the Hamburg Bone Tumor Registry. A total of 9,895 biopsy/resection specimens have been examined. Frozen section diagnosis in combination with imprint cytology can be performed as for other tumors. Routine techniques are paraffin embedding, if necessary following EDTA decalcification, and plastic embedding. By means of contact x-rays good insights can be gained into the extent of bone matrix formation or the osteolytic activity of bone tumors. These findings correlate well with the results of clinical imaging. In special cases DNA analysis and various immunohistological reactions can contribute substantially to a correct diagnosis. So far cytogenetics and molecular biology are of only limited use in routine diagnostics, apart from Ewing's sarcoma. In spite of sufficient experience of many registries there are still a number of inaccurately defined primary bone tumors with uncertain biology, for example low grade malignant osteosarcoma. A clear characterization of these tumors using new techniques is a task for the future.