Nucleolar organizer regions in soft tissue tumours

The diagnostic perspectives of the combination of silver NOR staining method with TV image analysis were tested in 138 soft tissue tumours. In addition to counting the dots per cell, we also measured the summed areas of dots within the nucleus. The so called "malignancy factor" (MF), i.e. the number of dots multiplied by summed areas of dots in one nucleus, was calculated. Tumours were divided into four groups: 1) benign, 2) benign with diagnostic difficulty, 3) intermediate malignant and 4) malignant. The number of dots, the summed area of dots and the MF were separately evaluated by the "t" test. Groups 2 and 3 were not distinguishable at all (p. - 0.788-0.863), while the others showed significant differences in the former values (p less than 3.5 x 10(-6) - 10(-6). When the number of dots was considered in itself, some overlaps occurred between the fourth and the other groups. With the determination of MF, however, no overlap was encountered at all. MF seems to be superior to traditional dot counting when malignant, intermediate and benign soft tissue tumours are to be distinguished.