Epithelial Membrane Antigen-positive Cells Research Articles

Hybrid Schwannoma-Perineurioma of the Gastrointestinal Tract

Soft tissue neoplasms with features of both schwannoma and perineurioma (hybrid schwannoma-perineurioma) have been increasingly recognized in recent years. To date, only a single case of this entity has been documented in the gastrointestinal tract (sigmoid colon). We herein describe 2 new cases of this entity. For comparison, we reevaluated 12 classic gastrointestinal schwannomas for the perineurial cell component. The 2 hybrid schwannoma-perineuriomas were detected incidentally in the gastric antrum and the vermiform appendix in a 50-year-old woman and a 17-year-old man during surgery for gastric GIST and appendicitis-like symptoms, respectively. None of the patients had neurofibromatosis 1 or 2. Patients were alive with no evidence of recurrence or new tumors at 8 and 12 months, respectively. The tumors measured 1.2 cm and 1.5 cm in size. Histologically, they showed prominent storiform, lamellar, and fascicular patterns. Notably, both lacked peripheral lymphoid cuffs and the trabecular pattern of gastrointestinal schwannomas. Both tumors coexpressed protein S100 (≥80%), CD34 (80%), and the perineurial cell markers (20% to 40% of tumor cells). The perineurial cell component formed alternating fascicles with S100-positive cells throughout the neoplasm. Reevaluation of 12 classic gastrointestinal schwannomas showed isolated claudin-1/epithelial membrane antigen-positive cells. However, 4 schwannomas (33%) strongly expressed glucose transporter-1 in most of the tumor cells indicating its limited specificity in this setting. Compared with gastrointestinal schwannomas, CD34 expression was stronger and more diffuse in hybrid schwannoma-perineuriomas. We conclude that hybrid schwannoma-perineuriomas are distinct from gastrointestinal schwannoma, both histologically and immunohistochemically.

Significance of epithelial membrane antigen in the work‐up of problematic serous effusions

Differentiation of reactive and/or atypical mesothelial cells from malignant epithelial cells in serous effusions remains a frequent diagnostic problem. Since epithelial membrane antigen (EMA) positive malignant cells in serous effusions have been reported in almost all adenocarcinomas and most malignant mesotheliomas, immunoreactivity for EMA is felt to be less useful than other antibodies in the workup of problematic serous effusions. However, immunostaining of reactive and/or atypical benign mesothelial cells for EMA has not been well studied, with only a few series reporting either weak or negative staining for EMA. This study was undertaken to evaluate how often reactive and/or atypical appearing mesothelial cells stain positively for EMA. One hundred eighty serous effusions (115 pleural, 55 peritoneal, and 10 pericardial) from 123 females and 57 males ages 20 to 89 yr were evaluated in which an antibody panel including EMA was performed on cell blocks (141 cases), cytospins (36 cases), or both (3 cases). Of the 100 cytologically positive cases, EMA immunoreactivity was present in 97/100 (97%) cases. One EMA negative case suspicious for a metastatic renal cell carcinoma was lost to follow-up and not included in the analysis. The remaining three negative cases consisted of malignancies not expected to have EMA positive cells (small cell carcinoma, neuroblastoma, and synovial sarcoma). Therefore, EMA was positive in virtually 100% of the remaining malignant cases. In the 78 cytologically negative cases, EMA positivity was present in 3/78 (3.8%) cases. Clinical follow-up of up to 14 mo in these three cases revealed no evidence of malignancy.(ABSTRACT TRUNCATED AT 250 WORDS)

Diagnostic Criteria OF Classical Carcinoids

The classical (mid-gut) carcinoids of the intestinal tract display a characteristic light microscopic morphology. However, sometimes intestinal tumours are seen resembling carcinoids and differential diagnostic difficulties arise. In the present study silver stains and immunoreactivities to chromogranin A + B, cytokeratins and epithelial membrane antigen (EMA) were evaluated as diagnostic adjuncts in six classical carcinoids and six intestinal carcinomas with carcinoid-like features. All classical carcinoids were argentaffin and argyrophil and contained a majority cell population with chromogranin immunoreactivity while only one carcinoid-like carcinoma was chromogranin-immunoreactive and the stained cells in that case represented a minority of the tumour cell population. The cytokeratins were shown to be non-discriminatory. However, EMA expression occurred in five intestinal carcinomas and in the majority of the tumour cells of four of these cases, while only one classical carcinoid displayed a few EMA positive cells. Thus, silver stains in combination with chromogranin A + B and EMA appears to be of value to discriminate between classical carcinoids and carcinoid-like intestinal carcinomas. Further when intestinal carcinoids and carcinoid-like carcinomas are diagnosed with the aid of various tumour markers both qualitative and quantitative considerations must be made.

Micrometastases in breast cancer: Long-term follow-up of the first patient cohort

“Micrometastases” can be identified in the bone marrow of patients with apparently localised breast cancer using an immunocytochemical stain for epithelial membrane antigen (EMA). Of 39 women who had marrow samples examined at the time of initial presentation (37), or with locally recurrent disease (2), 13 (33%) had samples which contained small numbers of EMA positive cells. 10 out of 23 (44%) lymph-node positive patients were marrow positive, compared to 1 out of 14 (7%) lymph node negative cases ( P = 0.03). Long-term follow-up (median 9.5 years) has shown that 11 out of 13 (85%) patients with micrometastases have developed metastatic disease compared to 8 out of 26 (31%) with negative bone marrow aspirates ( P < 0.05). The small number of EMA positive cells detected in bone marrow samples probably reflects the high metastatic potential of primary or recurrent cancers rather than established microscopic deposits; it is not yet clear whether the finding of such micrometastases will act as an independent variable compared to established prognostic factors.

Epithelial Membrane Antigen. Its use in the cytodiagnosis of malignancy in serous effusions.

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.