| Abstract|| |
In effusion cytology, a clear distinction between reactive mesothelial cells and metastatic adenocarcinoma cells is sometimes challenging mainly due to similarities in the cytomorphological features. In such cases for definitive diagnosis, paraffin-embedded cell block examination and immunohistochemistry are helpful in making this distinction. MOC-31 is one of the proposed immunomarker for adenocarcinoma cells. We undertook to evaluate the role of MOC-31 as a marker for identifying adenocarcinoma cells in effusion specimen. A total of 185 paraffin-embedded cell blocks of effusion samples were identified, of these 111 cases were of metastatic adenocarcinoma. MOC-31 was positive in 101 of the 111 cases of metastatic adenocarcinoma. Minimal focal cytoplasmic staining was also seen in 7 of the 74 cases of reactive mesothelial cells, but these were taken negative as they did not show membrane positivity. The sensitivity and specificity of MOC-31 for metastatic adenocarcinoma cells were 92.5%, and 100% respectively, positive and negative predictive value (NPV) was 100% and 91.14%, respectively. MOC-31 can be used as a reliable marker in effusions for distinguishing metastatic adenocarcinoma from reactive mesothelial cases.
Keywords: Adenocarcinoma cells, effusion cytology, MOC 31, reactive mesothelial cells
|How to cite this article:|
Patil B, Shivkumar V, Gangane N. Utility of MOC-31 monoclonal antibody in differentiating metastatic adenocarcinoma cells and reactive mesothelial cells in effusion cytology. Indian J Pathol Microbiol 2018;61:90-3
|How to cite this URL:|
Patil B, Shivkumar V, Gangane N. Utility of MOC-31 monoclonal antibody in differentiating metastatic adenocarcinoma cells and reactive mesothelial cells in effusion cytology. Indian J Pathol Microbiol [serial online] 2018 [cited 2020 Jan 18];61:90-3. Available from: http://www.ijpmonline.org/text.asp?2018/61/1/90/228202
| Introduction|| |
In cytology of effusions, a common difficulty is differentiation between reactive mesothelial cells and adenocarcinoma cells because of cytomorphological resemblance with each other.
To give an accurate diagnosis based on conventional cytology only, is often challenging and at times becomes difficult., Various mesothelial and epithelial markers are available to differentiate between reactive mesothelial cells and metastatic adenocarcinoma. Majority of the studies ,,,,,, have used panels of different antibodies for mesothelial, and adenocarcinoma cells and this has cost implications. Amidst the various antibodies, MOC-31 was found to be a reliable marker and so can be used for differentiating metastatic adenocarcinoma and reactive or malignant mesothelial cells.,, In the present study, we evaluate the use of MOC-31 as a single immune marker to differentiate metastatic adenocarcinoma cells from reactive mesothelial cells in cell block effusion samples.
| Materials and Methods|| |
Specimen included were pleural fluids, peritoneal fluids, pelvic, and peritoneal washings. Specimens were obtained from patients with a clinical suspicion or a history of malignancy. Relevant clinical details were retrieved from the Hospital Information System.
The samples were immediately processed. Minimum 20 ml of sample was taken and divided into two equal parts. At least 10 ml of the specimen was centrifuged for 10 minutes at 1500 revolutions per minute (rpm), and smears were prepared from the sediment to establish the cytomorphological diagnosis. The second part of minimum 10 ml fluid was used for cellblock technique. The cell block was embedded in paraffin wax.
Unstained sections of the tissue block cut at 4–6 μm thickness were subjected to immunostaining using MOC-31 as primary antibody. (Cell Morque, Mouse monoclonal antibody, Ref No. 248M-14, Lot number 1220507-C) with antigen retrieval (Citrate buffer [pH 6.0]) and 33 Diaminobenzidine as chromogen. Relevant positive and negative tissue control were included in each run. Distinct membrane staining in cells, irrespective of cytoplasmic staining was considered as positive result.
All cases with positive immunostaining were correlated with the cytological diagnosis and clinical follow-up. The sensitivity, specificity, positive, and negative predictive values of MOC-31 as a marker of metastatic adenocarcinoma in effusion cytology specimen was calculated.
Ethical clearance was obtained from the Institutional Ethics Committee.
All data of our study were entered in Microsoft Excel sheet, and statistical analysis was done.
| Results|| |
A total of 185 (111 cases of proven metastatic adenocarcinoma and 74 cases of reactive mesothelial hyperplasia with no known primary) cell block samples were the study subjects of the present study. Out of the total 185 study samples, 115 (62.67%) were pleural fluid, 48 (25.94%) samples were ascitic fluid, 15 (8.10%) were peritoneal washing, and 7 (3.78%) were pelvic washing. All 111 metastatic adenocarcinoma cases were subjected to MOC-31 immunostainig. In 101 out of total 111, cases it was positive [Figure 1] and [Figure 2], and in 10 cases, MOC-31 staining was negative [Table 1].
|Table 1: Results of immunostaining with MOC 31 in 111 metastatic adenocarcinoma cases with primary tumor sites|
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|Figure 1: Cellblock section from pelvic washing showing positive reaction with MOC-31 stain in a case of metastatic adenocarcinoma of ovary along with few lymphocytes (MOC-31, ×40)|
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|Figure 2: Cellblock section from ascitic fluid showing positive reaction with MOC-31 immunostain in a case of metastatic signet ring cell carcinoma of stomach (MOC-31, ×40)|
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All 74 cell blocks of reactive mesothelial hyperplasia were negative for MOC-31 immunostaining, 7 out of 74 cases showed minimal focal cytoplasmic staning but none of the 7 cases showed membrane positivity, so these cases were considered as negative [Figure 3].
|Figure 3: Cellblock section from pleural fluid showing focal diffuse cytoplasmic reactivity of mesothelial cells with MOC-31 immunostain (MOC-31, ×40)|
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The sensitivity of MOC-31 as an immunomarker for diagnosing metastatic adenocarcinoma in paraffin-embedded tissue cell blocks of the body cavity effusion samples was 91%, specificity was 100%, negative and positive predictive value (PPV) was 88.10% and 100%, respectively.
| Discussion|| |
Recognizing adenocarcinoma cells in effusion cytology specimens is often challenging mainly due to the presence of cytomorphologically similar reactive mesothelial cells. Most of the effusion can be diagnosed correctly by cytomorphological features alone; however, there remain few cases in which the differentiation becomes difficult mainly due to morphologic overlap of the constituent cells.
MOC-31 is a reliable marker for distinguishing between adenocarcinoma and reactive mesothelial cells.,,
In the present study, the sensitivity of MOC-31 for diagnosing metastatic adenocarcinoma in tissue cell blocks of the body cavity effusion samples was 91%, specificity was 100%. The MOC-31 immunostain sensitivity ranged from 70% to 100% in different studies.,,,,, In the study done by Su et al. out of total 60 cases of metastatic adenocarcinoma, MOC-31 was positive in only 42 cases with a sensitivity of 70%, this low sensitivity could be attributed to the fact that in this study, criteria for positivity with MOC-31 was both membrane and cytoplasmic reactivity whereas in the present study and also in other studies.,,,,,,, Membrane staining irrespective of cytoplasmic staining was taken as positive reaction with MOC-31 immunostain.
In majority of the studies,,,,,, the specificity of the MOC-31 immunostain was 100%. However, in the study done by Su et al. and Saleh et al., the specificity of MOC-31 stain was 92.5% and 93%, respectively, this was mainly because weakly expressed MOC-31 immunostain in the cytoplasm of reactive mesothelial cells and mesothelioma cells were considered as positive reactivity in these studies. The PPV and NPV with MOC-31 stain for metastatic adenocarcinoma cells in the present study were 100% and 88.10%, respectively. In the study done by Morgan et al., the PPV was 100%, and NPV was 95%. The PPV and NPV of the present study are almost similar to the values in the study done by Kundu and Krishnamurthy  in which PPV and NPV was 100% and 92%, respectively.
There are very few studies  in which MOC-31 has been used as the lone immunomarker to differentiate metastatic adenocarcinoma cells and reactive mesothelial cells.
All the 74 cell blocks which were diagnosed as reactive mesothelial hyperplasia were negative for MOC-31 immunostaining. 7 (9.45%) cases had weak focal/isolated cell immunoreactivity with MOC-31; all these 7 cases were considered as negative for MOC-31 immunostaining as there was no membrane staining of the cells.
Hecht et al. in their study observed positive staining with MOC-31 in scattered mesothelial cells in 9 out of 112 reactive mesothelial cases, similarly Su et al. also noted in their study, two cases of reactive mesothelial cells and 1 case of mesothelioma expressed weak reactivity. Similar to the findings of the present study, Kundu and Krishnamurthy  also observed weak and focal staining with MOC-31 in 13% of reactive mesothelial/mesothelioma cases, but the characteristic membrane staining was absent, so it was considered as negative for MOC-31 immunoreactivity.
| Conclusion|| |
We noted that MOC-31 is a very good immunomarker for differentiating metastatic adenocarcinoma cells from reactive mesothelial cells in effusion samples and can be used as stand-alone marker. Interpreting membrane MOC 31 staining as the criteria of positive reactivity regardless of cytoplasmic staining helps to avoid false positive diagnosis.
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Conflicts of interest
There are no conflicts of interest.
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Department of Pathology, Mahatma Gandhi Institute of Medical Sciences, Sevagram, Wardha - 442 102, Maharashtra
Source of Support: None, Conflict of Interest: None
[Figure 1], [Figure 2], [Figure 3]