Further Observations on Paget's Disease of the Nipple

Summary

It was previously suggested that the clear and dark cells of Paget's disease might represent neoplastic counterparts of the basal clear cells and superficial eosinophilic cells, normally found within the mammary epithelium. Both the Paget cells and normal ductular epithelium have now been investigated by electron microscopy. The Paget clear and dark cells differed considerably in cytoplasmic ultrastructure. Comparison with the components of the normal ductule revealed that, whereas the Paget dark cells closely resembled the superficial dark cells of the ductular lining, the Paget clear cells differed morphologically from the basal clear cells of the mammary epithelium. They resembled, however, a clear cell component of the superficial layer of the ductular lining, the existence of which had not been previously appreciated on light microscopy. The significance and interrelationships of the clear and dark cell variants, both normal and neoplastic, are, however, not understood.