The ultrastructure of medullary carcinoma of the breast

Lymphoepithelioma-like carcinoma of the breast. Report of a case with the first electron microscopic study and review of the literature

Lymphoepithelioma-like carcinoma (LELC) is a tumor which occurs outside the nasopharynx and has morphological features identical to nasopharyngeal lymphoepithelioma. LELC of the breast (LELC-B) is uncommon, and its resemblance to medullary carcinoma of the breast (MC-B) obscures distinction between these two tumors. We report a case of LELC-B occurring in a 47-year-old woman. The tumor consisted of multinodules without circumscription. The tumor cells mainly exhibited loose clusters being permeated by numerous lymphocytes. The tumor cell clusters showed inconspicuous margins, which were far from syncytial patterns. The epithelial nature of the tumor cells was demonstrated by positivity for epithelial membrane antigen, AE1/AE3 and CAM5.2. Furthermore, glandular differentiation of the tumor cells was confirmed using electron microscopy for the first time. Epstein-Barr virus (EBV) was not detected using either in situ hybridization or polymerase chain reaction. These findings, together with former reports of LELC-B, suggest that the distinction between LELC-B and MC-B depends on whether circumscription and syncytial growth patterns exist. The other findings, including absence of EBV and immunohistochemical aspects of the tumor cells, are not considered different thus far. Although the prognosis of LELC-B is thought to be favorable, which is also similar to MC-B, distant metastasis was detected in the present case. To confirm the clinicopathological entity of these two tumors, it is important to recognize the difference between LELC-B and MC-B.

Medullary carcinoma of the breast: an ultrastructural morphometric study of nine cases

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

High endothelial venule and immunocompetent cells in typical medullary carcinoma of the breast

The characteristics of immunocompetent cells and their role in killing tumour cells in typical medullary carcinoma of the breast (TMC) have been investigated morphologically. Formation of high endothelial venule (HEV)-like vessels in tumour cell nests, the distribution of macrophages, T-zone histiocytes, T- and B-lymphocytes, the ratios of CD4+/CD8+, and natural killer (NK) or NK-like T-cells were examined in five cases of TMC. These results were compared with controls which consisted of three cases of ductal carcinoma with intense lymphocytic infiltration (control I) and four cases of ductal carcinoma with scanty lymphocytic infiltration (control II). An increased incidence of HEV-like vessels with migration of lymphocytes and a higher number of CD8+ lymphocytes with interleukin-2-receptor expression, as well as numerous CD57 cells, were noted in the tumour nests of TMC as compared with those of control groups. Furthermore, large granular lymphocytes, large lymphocytes invaginating tumour cells and necrotic tumour cells were observed electron microscopically. These findings indicate that infiltrating lymphocytes in TMC are activated and become effector cells that can kill the tumour cells by mechanisms similar to those of NK cells. The activities of immunocompetent cells in TMC appear to contribute to a favourable prognosis in TMC of the breast.

The ultrastructure of medullary, atypical medullary and non-medullary carcinomas of the breast

Three medullary, eight atypical medullary and four non-medullary carcinomas of the breast were studied by transmission electron microscopy. Detailed comparison of a number of structural, cytoplasmic and nuclear features failed to confirm previous suggestions that medullary carcinoma cells have a distinctive ultrastructure. Electron microscopy is thus unlikely to be useful in the differential diagnosis of the tumours, nor does it suggest a basis for the good prognosis of medullary carcinoma.