Evaluating marrow margins for resection of osteosarcoma. A modern approach.

Intraoperative evaluation of bone marrow margins by frozen section analysis is a common practice in the surgical treatment of osteogenic sarcoma. The purpose of this study was to assess the clinical use of intraoperative marrow margin evaluation to rule out occult intramedullary tumor extension in osteosarcoma surgery. One hundred twenty-eight consecutive patients with high grade osteosarcoma diagnosed between 1988 and 1996 (Group 1) were reviewed retrospectively and compared with 92 consecutive patients treated from 1979 to 1984 (Group 2). Eighty-five patients in Group 1 met the inclusion criteria of having high grade intramedullary lesions of the long bones observed on preoperative magnetic resonance imaging evaluation of the lesion and intraoperative frozen section analysis of the bone marrow margin. Thirty-three patients in Group 2 met the same inclusion criteria with the exception of having preoperative magnetic resonance imaging. Ninety-two marrow margins in Group 1 and 33 marrow margins in Group 2 were evaluated by frozen section. All 92 marrow margins in patients in Group 1 were negative by frozen section analysis and permanent histologic analysis. Of the 33 marrow margins in patients in Group 2, three (9.1%) were reported positive for tumor. Of these, one was found to be a false positive result on permanent pathologic examination. In addition, one false negative frozen section result was found, which was positive for tumor on permanent pathologic examination. The difference in true positive results of marrow margins between Group 1 and Group 2 was statistically significant. Intraoperative marrow margin evaluation by frozen section is not mandatory with modern imaging techniques. Preoperative evaluation of tumor extent using magnetic resonance imaging and intraoperative evaluation of the specimen by the pathologist (done by bivalving the specimen) are reliable methods to ensure adequate surgical margins in most cases of conventional osteosarcoma of the long bones.