Usefulness of cytofluorometric DNA ploidy analysis in distinguishing benign cartilaginous tumors from chondrosarcomas

In this study, we undertook to prove the usefulness of cytofluorometric DNA ploidy analysis in distinguishing benign cartilaginous tumors from chondro sarcomas. We analyzed the DNA ploidy of 47 cartilaginous tumors using DNA c ytofluorometry, which is more sensitive than flow cytometry. AU of these tu mors were classified into six groups on the basis of clinical, radiologic, and histologic criteria The 25 tumors in the No, 1 group showed no histolog ic signs of malignancy regardless of their clinical signs. The four tumors in the No. 2 group showed histologic signs of malignancy, but had benign cl inical signs like small bone origin or Oilier's disease. The No, 3 group (1 3 tumors), No. 4 group (four tumors), and No, 5 group (three tumors) were c onventional grade I, II, and III chondrosarcomas, respectively, and the No, 6 group included three dedifferentiated chondrosarcomas. Tumor cells isola ted from fresh tumor materials treated with papain and collagenase were sme ared on a glass slide and their nuclear DNA was stained with propidium iodi de. The DNA content of each cell was measured by a cytofluorometer as fluor escence intensity. The results of this study showed that all of the tumors in the No. 1 group had a diploid pattern with a significantly lower (P<.001 ) cell proliferative activity than the grade I chondrosarcomas in the No. 3 group, all of which had a diploid pattern. Cytofluorometric analysis also indicated that grade II and III chondrosarcomas in the No. 4 and 5 groups h ad a higher frequency of hyperdiploid cells (%HDC), including aneuploid and polyploid cells than grade I chondrosarcomas, Importantly, all of the grad e I chondrosarcomas showed a %HDC >8%, whereas all of the tumors in the No. 1 and 2 groups showed a %HDC <8%. Therefore, we believe that a %HDC value of 8% is borderline between biologically benign and malignant states in car tilaginous tumors. Four of five patients with aneuploid chondrosarcoma had tumor recurrence and two of these patients died of metastatic disease, alth ough all of the patients except for one with diploid chondrosarcoma were co ntinuously disease free after surgery. Based on these results, we concluded that the data of DNA ploidy analysis, especially cell proliferative activi ty expressed as %HDC, is more reliable and clinically more useful than the histologic and clinical signs of malignancy in distinguishing benign cartil aginous tumors from chondrosarcomas and even from low grade chondrosarcomas .