DIAGNOSTIC VALUE OF SILVER-STAINED NUCLEOLAR ORGANIZER REGIONS IN OSTEOSARCOMA, FIBROUS DYSPLASIA AND OSSIFYING FIBROMA OF THE JAWS

It is sometimes difficult to recognize a jaw lesion as osteosarcoma, ossifying fibroma or ‎fibrous dysplasia in routine hematoxylin and ‎eosin staining and a more accurate technique is needed to differentiate these ‎lesions. ‎Many studies have shown the potential usefulness of silver-stained nucleolar organizer region (AgNOR) parameters for the diagnosis of various neoplasms. This study was carried out on 42 archival biopsy specimens of jaw lesions including 14 fibrous dysplasias, 14 ossifying fibromas and 14 ‎osteosarcomas (10 well differentiated and 4 poorly differentiated). Number of AgNORs was evaluated on formalin-fixed, paraffin embedded sections. The mean AgNOR counts showed significant differences between these lesions. The mean counts of AgNORs were < 1 ‎for fibrous dysplasia, 1 to 2.5 for ossifying fibroma and well differentiated osteosarcoma, and > 6 for poorly ‎differentiated osteosarcoma. By considering a cutoff point of 1.81-2.5 for well differentiated osteosarcoma and 1-1.8 ‎for ossifying fibroma, well differentiated osteosarcoma can be differentiated from ossifying fibroma with a sensitivity of ‎90% and a specificity of 64.3%. The area under the ROC curve was 0.84. ‎The results in this study indicate that AgNOR staining is a useful technique for differential diagnosis of osteosarcoma, ossifying fibroma and fibrous dysplasia of jaws when it is difficult to recognize these lesions in routine hematoxylin and ‎eosin staining.