Usefulness of Nucleolar Organizer Region Staining in Gastric Myogenic Tumors: Correlation with Ploidy by DNA Flow Cytometry

A silver-staining technique to identify nucleolar organizer region-associated proteins (Ag-NOR) was applied to 55 gastric myogenic tumors. The mean numbers of Ag-NOR in the nucleus were: leiomyoma (30 cases), 2.0 + 0.6 (mean + SD); low-grade leiomyosarcoma (11 cases), 3.0 + 0.7; and high-grade leiomyosarcoma (14 cases), 3.9 + 0.7. The Ag-NOR counts were compared with DNA ploidy as determined by flow cytometry in 46 tumors. The Ag-NOR counts were significantly different in the aneuploid leiomyosarcomas (4.1 + 0.6: mean + SD) and diploid leiomyosarcomas (2.9 + 0.6: mean + SD). Thus, this parameter may serve as an objective histological discriminant for malignancy.