Morphometric and cytophotometric investigations of lobular neoplasia of the breast with ductal involvement.

The two different types, A and B, of in situ lobular neoplasia of the breast can be distinguished by cytomorphological means. DNA-measurements of type A are preponderantly diploid while those of type B vary from diploidy to hyperteraploidy with a maximum in the hyperdiploid range. The results indicate a higher potential of malignancy in type B. Homogenous ductular cell proliferations in the immediate neighbourhood of a lobular neoplasia display virtually the same distribution of DNA-values. Such evidence suggests that ductular changes and concomitant intralobular lesions have a common genesis, showing also a similar tendency towards malignant changes.