The authors present examples on how to use cellular
DNA distribution in support of diagnosis, and also to predict
biological behavior of mesenchymal tumours. In cases of smooth muscle tumours of the prostate and the uterus, on the basis of histological pattern, it was not possible to distinguish between bizarre cell (pleomorph)
leiomyoma and
leiomyosarcoma. The prostate tumour showed an euploid
polyploid cellular
DNA distribution pattern, supporting the diagnosis of benign pleomorph
leiomyoma. On the other hand, the uterus tumour showed an
aneuploid DNA content with a high S-phase fraction that is characteristic of malignant lesions. Cellular
DNA content analysis has helped to estimate the
biological behavior of a gastrointestinal stromal tumour originating from the stomach and a retroperitoneal dedifferentiated type of a
well differentiated liposarcoma. Small, diploid tumours (< 5 cm in diameter) with a low S-phase fraction behave like benign tumour or malignant tumour with a low malignant potential. The gastrointestinal stromal tumour was diploid with 8% S-phase ratio, therefore we could predict favorable outcome. It means that control examination is required less frequently. Prognostically, the dedifferentiated type of
well-differentiated liposarcoma differs from the common
well differentiated liposarcomas; the well differentiated part of this tumour consisted of only one diploid subpopulation with a low S-phase ratio, while the poorly differentiated areas contained a diploid and an
aneuploid cell population with a significantly higher S-phase fraction than that of diploid one.
Aneuploidy and rapid proliferation rate refer to increasing genetic instability, with a clonal selection for development of a more aggressive cell population, thus control examination is required more frequently.