MEDULLARY CARCINOMA OF THE BREAST - AN ULTRASTRUCTURAL MORPHOMETRIC STUDY OF 9 CASES

Ultrastructural and morphometric features of 10 medullary carcinomas o f the breast (MC) were investigated. Cases with a long follow-up were selected by applying stringent histologic criteria. All tumors had a h omogeneous appearance by light microscopy. Under transmission electron microscopy, they showed occasional intracellular lumen formation or k eratinization. In one tumor squamous differentiation was prominent and diffuse. Tumors with lymph node metastases possessed over 40% more de smosomes than nonmetastatic tumors. The number of cells with three or more nucleoli per nuclear section was significantly higher in metastat ic than in nonmetastatic tumors (p = .02). Classic cases of MC of the breast display a relatively uniform appearance. However, subtle differ ences can be identified between metastatic and nonmetastatic tumors by ultrastructural morphometry. Although these differences are not assoc iated with changes in the outcome of patients in this study, they seem to bear some relationship to the peculiar behavior of MC.