Epithelial Membrane Antigen: Its Use in the Cytodiagnosis of Malignancy in Serous Effusions

Abstract

The cytological distinction between reactive mesothelial and malignant cells frequently causes problems for the diagnostic cytologist. In order to determine whether an immunocytochemical method might help resolve these difficult cases, we have stained smears from 309 serous effusions from 246 patients for the Epithelial Membrane Antigen (EMA). The EMA staining was classified as strong, weak or negative. Carcinoma cells (as diagnosed by conventional cytology) stained strongly for EMA in 63 of the 116 positive smears (54%). Five out of 15 (33%) of cytologically suspicious smears from patients with known carcinomas gave a strong EMA stain. Of particular interest were three effusions in which malignant cells were not identified in conventionally stained smears and in which a small number of EMA positive cells were identified. The EMA positive cells were subsequently restained by the Papanicolaou method and identified as malignant on retrospective morphological examination.

The use of histological and immunohistochemical markers to distinguish pleural malignant mesothelioma andin situ mesothelioma from reactive mesothelial hyperplasia and reactive pleural fibrosis

“…Although six cases of reactive mesothelial hyperplasia and six cases of reactive pleural fibrosis also showed focal positive staining, the extent and intensity of staining were considerably less than with mesothelioma. These results are in accordance with published data on both histological 9 and cytological specimens, [11][12][13] where focal or equivocal positivity has also been described in reactive cases. Therefore, although one should be aware that focal positive staining for EMA may occur in reactive mesothelial hyperplasia, the pattern appears sufficiently distinct for diffuse linear staining to be highly suggestive of neoplasia.…”

“…Immunohistochemistry is now widely available, but despite an abundance of antibodies for differentiating between mesothelioma and other malignancies, there are comparatively few that distinguish reactive changes from neoplasia. 10 These include epithelial membrane antigen (EMA), 9,[11][12][13] p53 protein, [14][15][16][17] and bcl-2, 18 but the results reported with these markers are sometimes contradictory.…”

Critical evaluation of monoclonal antibody staining in breast carcinoma.

“…3 antibody in this series of breast carcinomas was not uniform. Overall, staining of antigen detected by EMA was greatest (median 18-2%, range 0-67 9%).…”

“…Other applications include the use of monoclonal antibodies to detect occult metastases or determine prognosis, and it is these roles that have attracted most attention in breast cancer. [2][3][4][5][6][7][8][9][10][11][12] Monoclonal antibodies reactive against breast carcinoma have been produced using several different immunogens. These include breast carcinoma metastases, milk fat globule membranes, breast carcinoma cell lines, lymph nodes from patients who have had a mastectomy, cytoplasmic intermediate filaments and receptor proteins.…”

Two leading lights of the Cytology world remembered

“…They also laid the foundations for others to visualise an academic role for Cytopathology. In fact, although their professional lives did not overlap substantially, they co‐authored at least two papers together in the 1980s …”