Atypical ductal hyperplasia, intraductal carcinoma, and frankly infiltrating ductal carcinoma of the breast were studied by electron microscopy. Atypical ductal hyperplasia was characterized by the presence of very abundant, irregular and frequently giant, polypoid microvilli. Intraductal carcinoma cells displayed very complex cell interdigitations. Conspicuous intracytoplasmic lumina were exclusively observed in infiltrating carcinoma cells. Anomalies in the cell membrane and its derivatives appear to be a common denominator of all these lesions. Both loosely arranged and tightly packed cytoplasmic filaments were much more abundant in infiltrating carcinoma cells than in either atypical hyperplasia or intraductal carcinoma. Phagocytosed leukocytes were often found within carcinomatous breast cells. The possible connection of this observation with immunologic phenomena remains obscure. Further ultrastructural studies may conceivably develop some of these features into more accurate diagnostic criteria for doubtful breast lesions.
Alpha‐cell neoplasms associated with hyperacidity and the Zollinger‐Ellison syndrome and beta‐cell neoplasms presenting with hypoglycemia were studied by electron microscopy. The severity of the clinical manifestations covered a broad range. The ultrastructural morphology of tumors within the same group varied considerably. Most conspicuous was the presence of abundant, mature, specific granules in cells from tumors associated with mild clinical syndromes. Conversely, cells from tumors presenting with the most severe symptomatology displayed few and immature‐looking granules. It is suggested that an alteration in the secretory mechanism of neoplastic alpha and beta cells may result in the production of substances structurally different from the secretory material of their nonneoplastic counterparts. These abnormal granules would have a similar or possibly even enhanced hormonal potency while their structural differences could explain their his‐tochemical negativity.
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