Abstract
This study was performed to obtain indices for clinically determining the degree of malignancy of pleomorphic adenomas. Nuclear DNA content and nuclear area of tumor cells were measured and analyzed in comparison with clinical and pathological observations.
Twenty-four cases of pleomorphic adenoma were studied. A control group consisted of seven cases of normal salivary gland, two cases of adenolymphoma, and five cases of malignant salivary gland tumor. Most of the cells were isolated from slices of paraffin embedded tumor masses removed from patients. Some cell samples were obtained from imprints of biopsy specimens. Following Feulgen staining, the nuclear DNA content and nuclear area were simultaneously measured with Vickers M86 scanning microdensitometer. The nuclear DNA content of the epithelial cells was calculated with the nuclear DNA content of a control lymphocyte put at 2.0c.
The results were as follows:
1) The DNA histogram of normal salivary gland showed one distinct peak at 2.0-2.5c. Cells with nuclear DNA content over 4.0c were not observed. The measurements of the nuclear area were distributed in and around the region of 30μ2.
2) In one case of adenolymphoma, the DNA histogram and the DNA-area scattergram showed a similar pattern to those of normal salivary gland cells. In another case, a small population of cells over 4.0c was observed and cells diffused slightly on the scattergram.
3) In the cases of malignant salivary tumor, the average values and the variances of the nuclear DNA content increased generally. Hyperploid cells over 4.0c and aneuploid cells were observed. The DNA histogram showed a shift rightward from normal modal C value, bi-peak or poly-peak. The scattergram showed a remarkable diffusion and a high correlation.
4) In the cases of pleomorphic adenoma, measurements of the nuclear DNA content and the nuclear area varied greatly, ranging from those close to the values of normal salivary gland to the values of malignant salivary tumor. The average values and the variances of the nuclear DNA content as well as the number of cells over 4.0c were apt to increase in patients who showed rapid progress of tumorgenesis, predominance of a solid pattern of tumor cells histologically and prolifelation like cords. Particularly in the cases where the measurements of the nuclear DNA content and the nuclear area resembled those of malignant salivary gland tumor, malignant potential tended to be high.
