Positive Staining For Epithelial Membrane Antigen Research Articles

A Comparative Evaluation of Immunohistochemical Markers for the Differential Diagnosis between Malignant Mesothelioma, Non-Small Cell Carcinoma Involving the Pleura, and Benign Reactive Mesothelial Cell Proliferation

Histopathological diagnosis of malignant mesothelioma (MM) and differentiating it from tumors infiltrating the pleura is very difficult. Distinguishing benign reactive mesothelial cell proliferation from MM also presents problems. The objective of this study was to evaluate the significance of selected immunohistochemical stains in differentiating MM from non-small cell lung cancers infiltrating the pleura and from benign reactive mesothelial cell proliferation. The material encompassed 86 cases of MM, 54 cases of NSCLC infiltrating the pleura, and 43 cases of benign reactive mesothelial cell proliferation. The MM cases were reclassified according to the WHO criteria (2004): epithelioid, 61 cases (71%), including well-differentiated papillomatous, 3 cases; sarcomatous, 6 cases (6.8%); fibrous, 4 cases (4.7%); biphasic, 15 cases (17.5%). A panel of immunohistochemical stains was used in this study. It included broad-spectrum antibodies to cytokeratins (CKAE1/AE3, CKMNF116), vimentin, epithelial membrane antigen (EMA), mesothelial cells (HBME1, CK5/6, calretinin), adenocarcinoma cells (BerEp4, B72.3, CEA, TTF1), antibodies enabling the assessment of proliferation (Mib1) and cell-cycle regulating proteins (p53). Coexpression of cytokeratins and vimentin was found in 63.9% of MM cases and cell-membrane reactions with EMA were seen in 58.9%. Positive staining for HBME1, CK5/6, calretinin, BerEp4, B72.3, CEA and p53 was obtained in 76.7%, 51.2%, 66.7%, 1.2%, 6.2%, 1.2% and 51% of the cases, respectively. None of the MM cases stained for TTF1. MM by WHO subgroups: Coexpression of cytokeratins and vimentin occurred in 55.7% cases of epithelioid MM, 93.3% of biphasic MM, 66.6% of sarcomatous MM, and in 100% of fibrous MM cases. Positive staining for HBME1, CK5/6, and calretinin was seen only in the epithelioid and mixed subtypes of MM; the respective percentages of positive reactions were: HBME1, 90.2% and 73.3%; CK5/6 58.2% and 53.3%; calretinin, 72% and 75%. Non-small cell lung cancers infiltrating the pleura: Coexpression of cytokeratin and vimentin was found in 17.6% of the cases, positive staining of membranes for EMA, in 13% cases. Positive staining for HBME1 was observed in 22.6% of the cases, for CK5/6, in 9.3%, for calretinin, in 2%, for BerEp4, in 72.2%, for B72.3, in 64.1%, for CEA, in 58.5%, and for TTF1, in 43.8%. Benign reactive mesothelial cell proliferation: Protein p53 was present in 9.3% of cases, whereas no positive staining for EMA was found. Differentiation of MM from non-small cell carcinomas: Among the antibodies used in the study, anti-HBME1 had the highest sensitivity (76.7%) but lowest specificity (77.4%). Staining for calretinin showed high specificity (99.8%), as did CEA and TTF1 (98.8% and 100%), with moderate sensitivity (66.7%, 58.5% and 43.8%, respectively). BerEp4 showed the highest sensitivity (72.2%) and specificity (98.8%). In diagnosing mesothelioma it is necessary to use a panel of immunohistochemical stains, which should contain antibodies to markers for adenocarcinoma and mesothelioma. Due to the high costs of such a study, a two-stage method is advantageous. The best combination of sensitivity and specificity was found for BerEp4, CEA, and TTF1 and for calretinin and HBME1. In the diagnosis of spindle-cell pleural tumors and the fibrous form of MM and benign reactive mesothelial cell proliferation , markers of mesothelial cells are noncontributory. Immunohistochemical staining fails to identify a reactive process, but a diffuse, positive stain for EMA and the presence of protein p53 support the diagnosis of MM.

Scalp Metastases of a Renal Cell Carcinoma

An 80-year-old man presented with a localized tumor of the right occipital scalp. The tumor was a 1-cm, bright red-purple, ulcerated, and crusted exophytic nodule on a smooth base (Figure 1). The lesion had grown asymptomatically over 18 months except for profuse bleeding induced by minimal trauma. It was extirpated with the clinical diagnosis of pyogenic granuloma vs. renal metastasis to the scalp. The patient's medical history included a transurethral prostatic resection 3 years earlier and, 1 year later, a right nephrectomy for a 2-kg kidney tumor verbally reported as "benign." The patient also had a 2-year history of untreated high blood pressure. Histopathologically, the excised tissue was an exo-endophytic nodule of a solid form composed of pleomorphic neoplastic cells with abundant clear cytoplasm, surrounded by fibrous collagen septae, blood vessel proliferation, and areas of hemorrhage (Figures 2 and 3). The histopathologic diagnosis of metastatic renal cell carcinoma was supported by immunohistochemistry with positive epithelial membrane antigen staining (Figure 4). Cytokeratins 7 and 20 were nonreactive. Laboratory studies revealed hematuria and elevated creatinine and urea nitrogen levels, but no malignant cells were observed in five urinary cytologies. Renal ultrasound showed the presence of two simple cysts in the left kidney and data compatible with chronic inflammatory disease.

A CASE OF SO-CALLED CARCINOSARCOMA OF THE ESOPHAGUS

A case of so-called carcinosarcoma of the esophagus in a 76-year-old man is reported. The tumor with ulceration (Borrman III type) was grossly found at Im-portion of the esophagus but not a polypoid lesion. Subtotal esophagectomy was performed surgically. With hematoxylin-eosin staining, the resected specimen revealed poorly differentiated squamous cell carcinoma with pleomorphic cell sarcomatous stroma. To examine the features of sarcomatous lesion, the tumor was stained immunohistochemically with antibodies against keratin (high molecular and low molecular type), epithelial membrane antigen (EMA), α1-antichymotryspin (α1-ACT) and vimentin respectively. The sarcomatous cells of this tumor showed the results of negative staining for keratin, positive staining for EMA, vimentin and α1-ACT, indicating characters of both epithelial and mesenchymal origin. The present case was considered so-called carcinosarcoma (squamous cell carcinoma with pleomorphic cell stroma) which derived from epithelial origin, and it was immunohistochemically suggested that cancer cells obtained a mesenchymal character at the level of intermediate filaments.

Immunohistochemical distribution of epithelial membrane antigen in bladder carcinomas as detected with a monoclonal antibody.

Expression of epithelial membrane antigen (EMA) was investigated immunohistochemically in 27 cases of bladder carcinoma using a monoclonal antibody. Normal urothelial epithelium showed EMA staining restricted to the upper layer of the surface epithelium. G-I transitional cell carcinomas demonstrated positive EMA staining which could be divided into the following 3 types; type 1, in which highly stained cells occurred in the upper layer of the neoplastic epithelium; type 2, in which the whole tumour focus was slightly stained; and type 3, in which cells strongly positive for EMA were scattered throughout the tumour focus. G-III (undifferentiated) transitional cell lesions exhibited irregular expression of EMA whereas squamous cell demonstrated specific intense EMA staining within keratinized tumour cells.

Immunohistochemical observations on binding of monoclonal antibody to epithelial membrane antigen in epithelial tumors of the oral cavity and skin

A total of 211 cases of benign and malignant tumors of epithelial origin were studied by the immunoperoxidase method to determine the distribution profile of epithelial membrane antigen (EMA) with the use of monoclonal antibody. Normal epithelial cells in the oral mucosa and skin were usually negative for EMA staining, as were epithelial cells in hyperplastic lesions and papillomas. Paget cells and tumor cells of Bowen's disease (carcinoma in situ) demonstrated a high incidence of EMA positivity, whereas the frequency in basal cell carcinoma was unexpectedly low. Squamous cell carcinomas revealed positive EMA staining of cytoplasmic membranes, and the antigen was also present in keratinized areas. EMA expression in squamous cell carcinoma generally showed a high incidence (85%) and was higher in keratinized lesions than in unkeratinized or less well-differentiated neoplasms. EMA distribution could be classified into two forms: one in which the cytoplasmic membranes demonstrate positivity and in which a positive cytoplasmic pattern is found in parakeratinized cells in malignant foci.