Medicine

Hultborn and Tornberg found that the degrees of cellularity and nuclear polymorphism and frequency of mitosis were of secondary importance, and that the only reliable criteria were those which illustrated the invasiveness of the tumour on the one hand and the host's resistance on the other. In a study of small tumours which pursued a lethal course despite the absence of axillary metastases, the only common morphological characteristics were a completely diffuse cellular infiltration at the periphery of the tumour and absence of any infiammatory cell infiltration or tendency to encapsulation. Cell pleomorphism and frequency of mitosis were quite unreliable as main criteria of high-grade malignancy. Nevertheless, those tumours with a more favourable clinical course in spite of large size or axillary metastases were naturally highly differentiated. The two factors, type of infiltration and differentiation, were considered the prime criteria in malignancy grading.