Diagnostic utility of sialosyl-Tn in discriminating carcinomatous cells from benign mesothelium in body cavity effusions

OBJECTIVE: Detecting malignant cells in the setting of reactive mesothelium can be difficult. Several techniques have been tried but without widespread acceptance. Sialosyl-Tn (STn) is an aberrantly glycosylated precursor of the MN blood group antigen frequently expressed in carcinomas and dysplastic epithelium. We investigated the STn monoclonal antibody for its clinical utility as an isolated stain to discriminate benign mesothelium from malignant cells. STUDY DESIGN: Cell block material from 72 cases of body cavity fluids were immunostained for STn using the avidin-biotin complex method without antigen retrieval. Slides were incubated overnight at 4 degrees C in a humidified chamber. RESULTS: Strong immunoreactivity was noted in 31/40 (77%) carcinomatous cases. Only moderate staining was noted in 1 of 28 (4%) benign effusions and weak staining in 5 (18%) additional benign cases. Specificity was 100%, sensitivity 78%, positive predictive value 100% and negative predictive value 76%. No staining was noted in four noncarcinomatous malignant effusions. CONCLUSION: STn may have diagnostic value in this cytologic setting as part of a diagnostic panel but not as an isolated stain.     

BCA-225 immunostain: is it of value in liver fine needle aspiration?

OBJECTIVE: To determine the utility of BCA-225 immunostain in differentiating hepatocellular carcinoma (HCC) from other malignant tumors in liverfine needle aspiration specimens. STUDY DESIGN: Cell block materialfrom 87fine needle aspirates of liver lesions, including 25 HCCs, 9 neuroendocrine carcinomas, 12 adenocarcinomas metastatic from the colon, 19 other metastatic adenocarcinomas, 13 other metastatic tumors and 2 cholangiocarcinomas, were immunostained with BCA-225 antibody using both the EnVision avidin-biotin method (Dako U.S.A., Carpinteria, California, U.S.A.), and the traditional avidin-biotin method, without antigen retrieval. Three independent observers evaluated the cases, and a consensus was reached. RESULTS: Strong immunostaining for BCA-225 in at least 10% of malignant cells was considered positive. Two of 25 HCCs, 9 of 19 adenocarcinoma metastases, 1 of 9 neuroendocrine carcinomas, 4 of 13 other metastases and 1 of 2 cholangiocarcinomas were positive. No colon metastases were considered positive. CONCLUSION: BCA-225 may help exclude the diagnoses of metastatic colon adenocarcinoma, neuroendocrine carcinoma and well- to moderately differentiated HCC in this cytologic setting.     

Diagnostic value of CA 15-3 antibody in detecting metastatic adenocarcinoma

OBJECTIVE: To determine the diagnostic value of CA 15-3 in detecting metastatic adenocarcinoma in body fluids using PreservCyt solution (Cytyc Corp., Boxborough, Massachusetts, U.S.A.) as collection fluid. STUDY DESIGN: Cytospin slides prepared from 72 cases with unequivocally benign or malignant diagnosis were studied. Of the cases studied, 34 were breast carcinomas, and 17 were benign pleural effusions. Slides were stained for CA 15-3 by using the avidin-biotin complex method. Cases were evaluated for the presence of membranous or cytoplasmic staining. The percentage of cells exhibiting strong staining was estimated for both breast carcinoma and all adenocarcinomas as a group. These results were compared with CA 15-3 staining exhibited by benign mesothelium. RESULTS: Ninety-one percent of the breast cancer cases studied showed a positive reaction with CA 15-3, while 6% of the benign mesothelium cases were positive (p < 0.01). The sensitivity of CA 15-3 was 91 % for breast carcinoma and 80% for all adenocarcinomas. Specificity was 94% for breast carcinoma and for all adenocarcinoma. CONCLUSION: CA 15-3 is a sensitive and specific marker for diagnosing adenocarcinoma in cytologic specimens using PreservCyt solution as collection fluid.     

Significance of immunocytochemical expression of E-cadherin, N-cadherin and CD44 in serous effusions using liquid-based cytology

OBJECTIVE: To assess the diagnostic utility of E-cadherin (E-cad), N-cadherin (N-cad) and CD44 to discriminate adenocarcinoma cells from benign and malignant mesothelial cells in body cavity fluids and to clarify the origin of cancer cells. STUDY DESIGN: A total of 120 ThinPrep (Cytyc Corp., Boxborough, Massachusetts, U.S.A.) cytologic specimens of serous effusions, which included 22 cases of reactive mesothelium, 6 cases of malignant mesothelioma and 92 cases of metastatic adenocarcinoma from various sites, were immunostained for E-cad, N-cad and CD44. RESULTS: Eighty-three of 92 metastatic adenocarcinomas (90.21%) expressed E-cad, while 1 of 6 malignant mesotheliomas and 1 of 22 cases of reactive mesothelium were positive for E-cad. All 6 cases of mesothelioma expressed N-cad, whereas most cases of metastatic adenocarcinomas were negative. CD44 immunoreactivity was seen in 18 of 22 (81.81%) benign effusions and in 21 of 92 (22.82%) metastatic adenocarcinomas. CONCLUSION: The combination of E-cad, N-cad and CD44 appears to be a useful panel for distinguishing metastatic adenocarcinoma, mesothelioma and reactive mesothelium and also for clarifying the exact histogenetic origin of cancer cells. This is of great importance in a few otherwise-insoluble cases because of differences in tumor treatment and prognosis.     

Identification of Malignant Cells In Serous Effusions Using A Panel of Monoclonal Antibodies Ber-Ep4, Mca-B-12 and Ema

A panel of three monoclonal antibodies (MoAbs) was tested on 29 benign and 53 malignant effusions with the aim of investigating its usefulness for the discrimination between benign and malignant lesions. The panel consisted of MoAbs directed against epithelial membrane antigen (EMA); MCA-b-12, reacting with a 350 kD glycoprotein with mucin-like characteristics present on human breast cancer cells and various other normal and neoplastic tissues, and Ber-EP4, directed against a 34 and 39 kD glycopeptide on human epithelial cells but not on mesothelium. Fifty-two (98%) of the malignant effusions reacted with EMA, 49 (92%) with MCA-b-12 and 44 (83%) with Ber-EP4. Fourteen per cent of benign effusions reacted with EMA, 17% with MCA-b-12 and 7% with Ber-EP4. All seven effusions obtained from patients with a malignant mesothelioma reacted with EMA, six of the seven cases staining intensively. None of the seven stained with Ber-EP4. MCA-b-12 did not react with the cells in one case of malignant mesothelioma. The results suggest that the combination of EMA and Ber-EP4 may be used to discriminate between benign and malignant cells and possibly also between adenocarcinoma and malignant mesothelioma. MCA-b-12 followed in general the reaction pattern of EMA, although often with a less intense staining reaction, making this antibody unsuitable for inclusion in the panel.     

Applications of monoclonal antibodies in clinical cytology as exemplified by studies with monoclonal antibody B72.3. The George N. Papanicolaou award lecture

The monoclonal antibody (MAb) B72.3, reactive with a high-molecular-weight, glycoprotein, tumor-associated antigen, designated TAG-72, has been previously shown to be reactive with formalin-fixed, paraffin-embedded tissue sections of adenocarcinomas of the ovary, colon and breast, but not a variety of normal adult tissues. It has demonstrated utility as an immunocytochemical adjunct for the diagnosis of carcinoma in cell blocks and cytocentrifuge preparations of human serous effusions, with selective reactivity for tumor cells (particularly adenocarcinoma) over reactive mesothelium. Using the avidin-biotin complex (ABC) method of immunoperoxidase staining and formalin-fixed, paraffin-embedded cell suspensions, MAb B72.3 detected tumor cells in effusions from all of 21 patients with adenocarcinoma of the breast. No reactivity was demonstrated in any cell type in benign effusions from 41 patients. In contrast, MAb B72.3 showed no reactivity to leukemic or lymphomatous effusions, or to mesothelial cells from malignant effusions. MAb B72.3 also detected adenocarcinoma cells in effusion specimens from 12 of 12 patients with adenocarcinoma of the lung and 16 of 16 patients with adenocarcinoma of the ovary. MAb B72.3 has recently been used with fine needle aspiration (FNA) biopsy specimens and the corresponding surgically excised tumors to determine cellular reactivity. Using the ABC immunoperoxidase method, fine needle aspirates and corresponding surgically excised tumors were analyzed for TAG-72 expression. Positive staining with MAb B72.3 was observed in needle aspirates of 27 of 27 adenocarcinomas and adenosquamous carcinomas of the lung, 17 of 21 adenocarcinomas of the breast, 6 of 6 adenocarcinomas of the colon and in carcinomas from other body sites. In contrast, 21 small-cell carcinomas of the lung, 13 malignant melanomas, 2 lymphomas and 2 sarcomas did not stain with the antibody. Benign lesions from the breast, lung, pancreas, parotid and thyroid also showed no staining. In many patients, tumor-bearing tissue had also been resected and was available for comparative examination with MAb B72.3. In more than 90% of these patients, the staining patterns of the tumor cells in the aspirates were found to be predictive of the patterns of antibody reactivity in the comparable surgically resected tumors. From these studies, it is concluded that MAb B72.3 defines a tumor-associated antigen that is expressed in neoplastic cells versus benign cells, that is most selectively expressed in carcinomas and that may be used as a novel adjunct for the diagnosis of neoplasms in effusions and in fine needle aspiration biopsies.     

Diagnostic utility of GLUT-1 expression in the cytologic evaluation of serous fluids

OBJECTIVE: To evaluate the extent to which adenocarcinomas in body cavity fluids express GLUT-1 in comparison to currently available markers for adenocarcinomas. STUDY DESIGN: Archival paraffin-embedded cell blocks of serous fluids from 25 cases of benign effusions containing reactive mesothelial cells and 39 cases of malignant effusions with metastatic adenocarcinoma (11 ovarian, 11 pulmonary, 9 gastrointestinal and 8 breast) were retrieved from the surgical pathology files. All cases were stained with antibodies for GLUT-1, Ber-Ep4, B72.3 and CEA. Positive staining was defined as distinct linear membrane staining for GLUT-1 and Ber-EP4, cytoplasmic staining for CEA, and cytoplasmic or membrane staining for B72.3. Strong staining in at least 10% of the tumor cells was required in order to consider the case positive for the particular marker. RESULTS: GLUT-1 was expressed in 72% (28 of 39) of cases of malignant effusions: 100% (11 of 11) from the ovary, 91% (10 of 11) from the lung, 67% (6 of 9) from the gastrointestinal tract and 12% (1 of 8) from the breast. None (0 of 25) of the benign effusions expressed GLUT-1. Malignant effusions expressed CEA in 74% (29 of 39), Ber-Ep4 in 85% (33 of 39), and B72.3 in 62% (24 of 39). Benign effusions expressed CEA in 3 cases and B72.3 in 2 cases. CONCLUSION: GLUT-1 is a useful marker that can be applied to cytologic specimens. It can be used as a reliable component of an antibody panel to distinguish reactive mesothelial cells from metastatic adenocarcinoma in particular adenocarcinomas of body cavity effusions, in particular adenocarcinomas of ovarian and pulmonary origin.     

Immunocytochemical Staining of Serous Effusions With the Monoclonal Antibody Ber-Ep4

Cytospin preparations were made from 102 serous effusions for immunocytochemical staining using a panel of monoclonal antibodies including a new monoclonal antibody Ber-EP4. On cytological examination, 32 fluids were reported to contain tumour cells consistent with metastatic adenocarcinoma; 66 contained benign cells only and three were reported to contain cells suspicious of malignancy. One effusion contained tumour cells consistent with malignant mesothelioma. Positive staining of the tumour cells with Ber-EP4 was observed in the 32 effusions (100%) which contained adenocarcinoma cells. No staining of the mesothelial cells in these 32 specimens was observed. Carcinoembryonic antigen, epithelial membrane antigen Ca2 and CD15 staining of tumour cells was noted in 53%, 50%, 50% and 9% of these cases, respectively. None of the mesothelial cells in the benign effusions stained with Ber-EP4. Nor did the malignant mesothelial cells in the only case of malignant mesothelioma. These findings suggest that Ber-EP4 is a valuable addition to antibodies available for the differential diagnosis of mesothelial cells and adenocarcinoma cells in serous effusions.     

The value of calretinin and cytokeratin 5/6 as markers for mesothelioma in cell block preparations of serous effusions

Objective: To determine the value of calretinin and cytokeratin (CK) 5/6 in discriminating mesothelioma from adenocarcinoma in serous effusion specimens. Methods: A total of 101 recent, histologically or clinically confirmed malignant effusions with immunostained cell block preparations were reviewed. The cases consisted of 34 mesotheliomas and 67 adenocarcinomas. This included 17 ascitic fluid and 84 pleural fluid samples. The adenocarcinomas included metastatic carcinomas from the breast (12), lung (19), stomach (3), colon (1), pancreas (2), ovary (6) endometrium (1) and 23 histologically confirmed metastases from unknown primary sites. The cases were assessed as negative or positive (>5% of cells stained). The staining pattern was recorded as cytoplasmic, cell membrane, nuclear or cytoplasmic and nuclear staining. Results: Calretinin staining was present in 97% (33/34) of the mesothelioma cases with a majority of them showing both cytoplasmic and nuclear staining (29/33). Only 3% (2/67) of adenocarcinomas were positive for calretinin, one being a lung adenocarcinoma and the other an adenocarcinoma of unknown primary site in an ascitic fluid. Cytokeratin 5/6 staining was also present in 33/34 (97%) of mesothelioma cases. Six (9%) adenocarcinomas were positive, including metastases from the lung (1), breast (1), ovary (2) and unknown primary site (2). Four of the six adenocarcinoma cases positive for CK5/6 were in ascitic fluids. No cases of mesothelioma were negative for both calretinin and CK5/6. Only one adenocarcinoma case, (which was from unknown primary site in an ascitic fluid sample), was positive for both markers. Conclusions: The results confirm that calretinin and CK 5/6 are useful markers for mesothelioma in effusion specimens. CK5/6 staining may be less useful for peritoneal fluid specimens where metastatic adenocarcinomas may be more likely to express the antigen. Further study of ascitic/peritoneal specimens is warranted. However, positive staining, particularly for both antigens, is highly indicative of a mesothelial origin for cells. The two markers make a useful addition to EMA and the panel of adenocarcinoma markers routinely applied to effusion specimens.     

Comparison of NCL-hTERT antibody reactivity and telomere repeat amplification protocol in situ in effusions

OBJECTIVE: To compare the performances of 2 methods, telomerase repeat amplification protocol (TRAP) in situ and antibodies to the hTERT protein, in assessing telomerase activity. STUDY DESIGN: TRAP in situ and immunohistochemistry with a commercial antibody (NCL-hTERT) was performed on 54 body cavity effusions. The results were compared and correlated to diagnosis. RESULTS: Thirty-four effusions from patients with verified malignant disease contained cytologically malignant cells. Both methods were positive in 33 of the cases, whereas only hTERT was positive in 1 case. Twenty effusions, all containing mesothelial cells, came from patients with benign conditions. In 2 fluids atypical, hyperplastic mesothelial cells were both TRAP in situ and hTERT positive. All remaining 18 fluids were TRAP in situ negative, whereas 12 of 18 were hTERT positive. Thus the results of TRAP in situ and hTERT immunohistochemistry disagreed in 1 of 34 (3%) malignant and 12 of 20 (60%) benign cases. CONCLUSION: The sensitivities for malignancy were similar for TRAP in situ and hTERT immunohistochemistry. The specificity of the applied hTERT antibody was significantly lower, due to hTERT reactivity in mesothelial cells.     

Detection of adenocarcinoma in peritoneal washings by staining with monoclonal antibody B72.3

Peritoneal washings are routinely performed in the staging evaluation of carcinomas of the ovary and in "second-look" explorations; major problems in the evaluation of these specimens continue to be the distinction between atypical mesothelium and adenocarcinoma and the identification in an otherwise inflammatory specimen of rare cells of adenocarcinoma, which may be undetected by the most trained individual. Monoclonal antibody (MAb) B72.3, reactive with an oncofetal, tumor-associated glycoprotein (termed TAG-72; MW greater than 1000 kd) expressed in a variety of epithelial malignancies but not generally expressed in benign or malignant mesothelium, was reacted with sections from the paraffin-embedded cell blocks of 185 peritoneal washings from 180 patients with extant cancer or a prior history of malignancy. One hundred four of the washings were initially interpreted as atypical mesothelium, with no evidence of malignancy; when reacted with MAb B72.3, 6 of these specimens demonstrated groups of metastatic adenocarcinoma cells not appreciated by the usual cytologic criteria. Of the 81 washings interpreted as showing cells of adenocarcinoma, 73 demonstrated expression of TAG-72 from both gynecologic and nongynecologic malignancies. In the remaining 49 cases without an associated malignant process, MAb B72.3 did not stain atypical mesothelium, but did react, however, with benign endometrial cells and müllerian inclusions in two cases. MAb B72.3 may be used as a diagnostic adjunct to the routine cytologic evaluation of malignancy in peritoneal washings; reactivity with MAb B72.3 may indicate the need for further evaluation to define the presence of a malignancy or an advanced cancer.     

Monoclonal antibodies in the cytodiagnosis of serous effusions

In order to assess the value of immunocytochemical staining as a method of discriminating between benign reactive mesothelial cells and malignant epithelial cells in serous effusions, we have studied the reactions of a panel of commercially available antibodies on cells harvested from 83 pleural and peritoneal fluids and compared the results with the clinical and cytological diagnoses. The antibodies used were raised against cytokeratin (PKK1), epithelial membrane antigen (EMA), carcino-embryonic antigen (CEA), pregnancy specific B1-glycoprotein (SP1) and leucocyte common antigen (LCA). Anti-CEA was positive in 16 of 39 effusions (41%) containing carcinoma cells. Pregnancy specific B1-glycoprotein (SP1) was positive in 33% of the same samples. Mesothelial cells did not stain with these antibodies. Thus anti-CEA and SP1 can be used to discriminate between benign mesothelial and malignant epithelial cells in effusions. Anti-PKK1 stained both benign reactive mesothelial cells and malignant epithelial cells and cannot be used to discriminate between these two cell types. Strong positive staining of malignant cells was noted with anti-EMA. However, as occasional weak staining of mesothelial cells was also noted, strong staining with this antibody may be regarded as suspicious but not conclusive of malignancy.     

Characterizing subpopulations of neoplastic cells in serous effusions. The role of immunocytochemistry

OBJECTIVE: To analyze the role of immunochemistry in serous effusions. STUDY DESIGN: We analyzed cell blocks of 18 pleural and 18 peritoneal effusions diagnosed as malignant (18), benign (14) and suspicious (4). They were immunostained by the avidin-biotin complex method with a panel of four monoclonal antibodies--CEA, Ber-EP4, LeuM1 (CD15) and p53--and, for lectins (Ulex europaeus) UEA-l, ConA and ConBr. RESULTS: Seventeen of the 18 cases of adenocarcinoma were positive for CEA (95%), 12 (66.6%) for Ber-EP4, 11 (61%) for CD15 and 11 (61%) for p53. Twelve of the 18 (66.6%) were positive for UEA-1, CEA, Ber-EP4 and CD15. UEA-1 did not react with mesothelial cells. p53 Gave a positive reaction in only one case, reactive mesothelial cells. ConA and ConBr reacted indiscriminately with benign and malignant cells; thus, it was not useful in distinguishing between these cells. CONCLUSION: In this context no antibody used alone is reliable for corroborating a diagnosis, but the selective use of a small panel of three markers (CEA, Ber-EP4 and LeuM1) can be very useful in solving diagnostic difficulties in the cytodiagnosis of serous effusions.     

p53 immunohistochemistry for distinguishing reactive mesothelium from low grade ovarian carcinoma

OBJECTIVE: To determine the utility of immunohistochemical staining for p53 in cell block material for distinguishing reactive mesothelium from borderline or low grade ovarian carcinoma. STUDY DESIGN: Paraffin-embedded cell blocks from paracentesis and pelvic wash fluid of 44 cases of ovarian carcinoma and 20 cases containing only reactive mesothelium were immunostained for p53 using monoclonal antibody DO-7. Tumor grades ranged from borderline to high grade and were serous papillary (33), clear cell (3), mucinous (2), endometrioid (2), mixed serous papillary/clear cell (3) and undifferentiated (1). The three authors independently evaluated the staining, including estimation of the percentage and intensity of positive nuclear staining. RESULTS: A separation of positive from negative cases was seen when staining intensity was considered the critical parameter; moderate to strong staining was considered truly positive. Seventy-three percent (8/11) of borderline tumors, 80% (8/10) of low grade tumors and 65% (15/23) of intermediate to high grade tumors showed moderate to strong positivity. Percentage of staining was a less-reliable parameter as 25% of negative cases were positive by this assessment. CONCLUSION: p53 Immunohistochemistry, using monoclonal antibody DO-7 combined with standard morphologic evaluation, may be useful in distinguishing benign reactive mesothelium from borderline or low grade ovarian carcinoma.     

GLUT1 antibody staining in thin-layer specimens of benign and malignant body cavity effusions

OBJECTIVE: To determine whether GLUT1 antibody could replace one or more of the currently used antiepithelial antibodies and to assess whether ThinPrep methodology is suited to immunocytochemical (ICC) evaluation. STUDY DESIGN: In a prospective study of 10 fluids containing malignant cells from cases of proven adenocarcinoma and 10 cytologically benign effusions, multiple slides were prepared by ThinPrep technology for staining with four commercially available antibodies and appropriate isotype-matched negative controls. The antibodies used were GLUT1, CEA, B72.3 and Leu-M1 (CD 15). Tissue sections and ThinPrep slides were used as positive controls. Specimens were batched to ensure similar conditions for all antibody reactions. RESULTS: Of the 11 cases ultimately proven to be carcinoma, GLUT1 and B72.3 stained 7 each (63.6%), and CEA and Leu-M1 6 each (54.5%). No false positive staining was encountered, but one case chosen as a benign control was shown to contain immunopositive cells by three of the four epithelial markers used; this case was therefore an occult true positive rather than a false positive. CONCLUSION: In this small but controlled prospective analysis, GLUT1 demonstrated strong positive staining, with sensitivity similar to that of currently used epithelial markers. Using GLUT1 in conjunction with B72.3, no cases of carcinoma were missed. GLUT1 could be used in a panel of antibodies designed to confirm the presence of adenocarcinoma. ThinPrep methodology, which enables multiple slides to be prepared after routine microscopy determines the need for ICC, appears suited to this adjuvant investigation.     

Immunohistochemical study of lysozyme, alpha 1-anti-chymotrypsin, tissue polypeptide antigen, keratin and carcinoembryonic antigen in effusion sediments

The cellular sediments of 42 malignant and 16 benign effusions (58 cases) were studied using the immunoperoxidase technique. Serial sections of formalin-fixed, paraffin-embedded residual sediments of effusions, sent for routine cytologic examination, were studied by commercially available polyclonal antisera against lysozyme, alpha 1-anti-trypsin, alpha 1-anti-chymotrypsin, tissue polypeptide antigen (TPA), a wide-spectrum anti-keratin, carcinoembryonic antigen (CEA) and, in single cases, thyroglobulin and prostate-specific antigen. A final definite diagnosis from histologic study of biopsy or autopsy specimens was known in all cases. All carcinomas, the mesotheliomas and the reactive mesothelial cells showed a positive reaction for TPA and, partly, the wide-spectrum keratin. Lysozyme could be demonstrated in the cells of the one proven malignant fibrous histiocytoma; all malignant epithelial cells were negative. Alpha 1-anti-chymotrypsin and alpha 1-anti-trypsin showed similar reactions: they were often positive in carcinoma cells of the breast, the bronchial system and the pancreas, in contrast to a mostly negative reaction in carcinomas of the stomach and ovary. CEA showed considerable differences; it was always negative in benign and malignant mesothelial proliferations but mostly positive in carcinomas of the stomach, pancreas and bronchial system. It was only positive in less than 20% of the carcinomas of the breast and always negative in the proven malignant effusions of primary carcinomas of the ovary and prostate. Studying a combination of several tumor markers is possible in serial paraffin-embedded sections and may be a valuable criterion in the cytologic diagnosis of effusions.     

Use of desmin immunohistochemistry to distinguish between mesothelial cells and carcinoma in serous fluid cell block preparations

OBJECTIVE: To evaluate the utility of immunohistochemical stains for desmin in discriminating mesothelial cells from adenocarcinoma in serous fluid cell block preparations. STUDY DESIGN: Cell block preparations from 22 cases (representing 18 patients) that were positive for carcinoma and 5 cases that were negative for malignancy were immunostained with an antibody to desmin. Positive staining was evaluated and scored semiquantitatively in both tumor cells and background mesothelial cells in the malignant cases and mesothelial cells in the negative controls. Staining was evaluated with a score of 0-3 for intensity and 0-5 for distribution. The sum of the two scores was recorded as the total score (TS). RESULTS: Mesothelial cells from all the carcinoma and benign cases stained with desmin (median TS = 5.5, range 4-8), typically strong in intensity and widespread in distribution. Positivity was observed in carcinoma cells in all cases, typically weak and focal (range 2-4). Using a total score of 4 as a cutoff for definitively positive staining, desmin staining was positive in mesothelial cells in 25/25 cases and carcinoma cells in 1/22 cases (P < .0001, Fisher's exact test). Additionally, using the Mann-Whitney ranked sum test on the 20 cases with evaluable mesothelial cells, the medians of the total scores for mesothelial cells (5.5) and carcinoma cells (2.5) were significantly different (P < .0001). CONCLUSION: A total score of > or = 4 was significantly associated with mesothelial cell staining. Use of desmin immunohistochemical staining in cell block preparations may be helpful in distinguishing between mesothelial cells and carcinoma.     

Diagnostic interest of the monoclonal antibody CA1 in malignant pleural effusion

The Ca1 antibody was used in an immunohistochemical procedure on smears of cells from 40 patients with malignant pleural effusion. The control group consisted of 25 benign pleural effusions with a high percentage of reactive mesothelial cells. The Ca1 Mc Ab was positive in 19 (79%) of the 24 pleural effusions with positive malignant cytology. In all the benign cases the Ca1 Mc Ab was negative (100% specificity). The Ca1 Mc Ab detected malignant mesothelial cells in two cases and was negative with reactive mesothelial cells and other nucleated cells present in the pleural effusion. We conclude that the Ca1 antibody offers a useful diagnostic method for malignant pleural effusions, when the morphological interpretation is doubtful.     

Utility of HBME-1 immunostaining in serous effusions

Utility of HBME-1 immunostaining in serous effusions
HBME-1 is an anti-mesothelial cell monoclonal antibody derived from human mesothelioma cells. We investigated 227 body cavity effusions to test its utility in differentiating mesothelioma from adenocarcinoma. HBME-1 outlined cell membranes in non-neoplastic mesothelial cells. Thick surface staining was observed on all mesotheliomas. HBME-1 reactivity was also detected in 24% of metastatic carcinomatous effusions. Most ovarian carcinomas (83%) reacted with this antibody, showing surface staining. Cytoplasmic HBME-1 immunoreactivity was observed in a small proportion of non-ovarian adenocarcinomas (14%). Despite its limited specificity, HBME-1 might be added to the battery of other markers of epithelial and/or mesothelial differentiation to be used in cases of suspected mesothelioma. Evaluation of suspicious cells should include careful study of the pattern of immunostaining.     

Galectin-3 is not useful in thyroid FNA

INTRODUCTION: Previous studies have suggested that galectin-3 immunohistochemistry may be useful in the fine needle aspiration (FNA) diagnosis of thyroid carcinoma as it has been reported to selectively stain carcinomas and not adenomas or goitres. METHODS: Fifty-one patients were included in a prospective study of galectin-3 in thyroid FNA; 88.2% were female and 11.8% male, mean age 53 years, range 25-87 years. Cell blocks were prepared and stained for galectin-3 if any cells were present in needle washings from the respective FNAs. RESULTS: Twelve of 51 (23.5%) of cell blocks contained epithelial cells. One benign and one inadequate FNA were negative for galectin-3 staining. One of five non-diagnostic FNA cases, a papillary carcinoma on final histology showed positive staining. Four follicular neoplasm/suspicious of carcinoma cases showed negative staining. One malignant FNA case, a papillary carcinoma showed positive staining with galectin-3 but three further carcinomas, two papillary and one follicular were galectin-3 negative. CONCLUSION: Galectin-3 immunohistochemistry does not appear to be a useful adjunct to diagnosis in thyroid FNA as it does not reliably distinguish malignant and benign lesions. Many thyroid aspirates are of low cellularity and are not suitable for cell block immunohistochemistry.