The distinction of adenocarcinoma from malignant mesothelioma in cell blocks of effusions: the role of routine mucin histochemistry and immunohistochemical assessment of carcinoembryonic antigen, keratin proteins, epithelial membrane antigen, and milk fat globule-derived antigen

The cytologic diagnosis of mesothelioma: are we there yet?

INTRODUCTION

Mesothelioma is a rare but highly aggressive malignancy with poor prognosis that frequently present with recurrent effusions. Establishing the diagnosis by cytology can lead to early diagnosis and treatment and consequently improve prognosis.

MATERIALS AND METHODS

This review examines the cytological diagnosis of mesothelioma in the context of its historical and morphologic evolution and provides an update of the current reporting systems. Clues to identify the mesothelial and malignant nature of the sample are detailed as well as the supporting ancillary tests.

RESULTS

Cytologically, the samples are overwhelmingly cellular and malignancy is recognized by both architectural and cytological atypia. Numerous variably sized clusters and enlarged cells are easily identified, some with papillary architecture and collagen cores. Recognizing the mesothelial nature of the cells and supportive immunostains are essential to rule out the differential diagnosis of metastatic carcinomas and reactive mesothelium. Current ancillary tests such as homozygous deletion of CDKN2A, loss of BRCA1-associated protein, and methylthioadenosine phosphorylase expression can provide further support of malignancy.

CONCLUSIONS

At this time with the aid of current ancillary tests and in the hands of cytopathologists with adequate experience with the interpretation of effusions, the diagnosis of mesothelioma can be established with accuracy in most cases.

Serous cavity metastasis: Evaluation of unknown primary

Malignant effusions can occur in patients with neoplasia. Once a metastatic diagnosis is confirmed, the primary site of origin of malignancy needs to be ascertained. This task can be challenging without a prior history of malignancy. In some patients their effusion may be the initial presentation of an underlying malignancy. Metastases usually present with a dual population of mesothelial and malignant cells. Combining cytomorphologic examination with ancillary testing such as immunocytochemistry can help identify the origin of the foreign malignant cell population. Helpful architectural clues include a single cell pattern, solid cell ball pattern, single file arrangement, papillary formation, psammoma bodies and background mucin. Useful cellular features include the presence of signet ring cells, small cells, pleomorphic and multinucleated giant cells, squamous cells, spindle cells and pigmentation. Rarely, despite an extensive work-up the primary site of origin for a malignant effusion may remain unresolved. This review article will be incorporated finally as one of the chapters in CMAS (CytoJournal Monograph/Atlas Series) #2. It is modified slightly from the chapter by the initial authors in the first edition of Cytopathologic Diagnosis of Serous Fluids.

Role of Ancillary Techniques in Fluid Cytology

The cytologic evaluation of serous effusions may be challenging for a number of reasons. Distinction of benign, reactive conditions from malignancy represents the main focus when examining these specimens. The morphologic diagnosis of malignancy may be difficult due to the relative paucity of abnormal cells. In other situations, cellularity is not an issue, but the ability to confidently identify a second, foreign (i.e., tumor) population within a background mesothelial cells on the basis of cytomorphologic features alone may pose problems. Cases with definitive morphologic evidence of malignancy may require additional studies in order to determine the tumor subtype and, in the case of carcinoma, the primary site of origin. Cases in which a definitive and precise diagnosis of malignancy is made may be optimal candidates for further molecular testing in order to gain prognostic information and guide personal therapeutic decisions. Finally, while an inflammatory or infectious condition can be suggested on the basis of cellular components and associated background elements, the identification of causative agent(s) may be difficult without additional studies. In all of these situations, the use of ancillary studies and techniques is critical; their utility and appropriate application are the subject of this review.

Claudin-4 immunohistochemistry is highly effective in distinguishing adenocarcinoma from malignant mesothelioma in effusion cytology

BACKGROUND

Adenocarcinoma can be challenging to distinguish from malignant mesothelioma in effusions, and this distinction often requires ancillary studies and clinical correlation. Immunohistochemistry for claudin-4, a tight-junction-associated protein, has recently been shown to distinguish adenocarcinoma from malignant mesothelioma, mostly in surgical specimens. Our aim was to validate and assess the immunoreactivity profile of claudin-4 in a large series of malignant effusions.

METHODS

We evaluated 159 malignant effusions (84 adenocarcinomas and 75 malignant mesotheliomas). Claudin-4 immunohistochemistry was performed on cell-block paraffin sections and scored for staining intensity, staining pattern (cytoplasmic versus membranous), and percentage of positive tumor cells. Appropriate positive and negative controls were used throughout.

RESULTS

All cases of mesothelioma were negative for claudin-4 (0 of 64). Eighty-three of 84 cases of adenocarcinoma were positive (99%); 1 case of serous carcinoma was negative. Most adenocarcinomas showed strong and diffuse membranous staining (71 of 84; 84%); 12 cases (14%) showed membranous staining of moderate intensity. The overall sensitivity for adenocarcinoma was 99% (83 of 84).

CONCLUSIONS

Claudin-4 immunohistochemistry effectively distinguishes adenocarcinoma from malignant mesothelioma with high sensitivity and specificity in the evaluation of malignant effusions.

Mesothelioma: path to multimodality treatment

Multimodality treatment of malignant pleural mesothelioma (MPM) with surgery, radiation therapy, and adjuvant or neoadjuvant chemotherapy is the sole path to extended survival for select patients with favorable prognostic factors. No single-modality approach has produced equivalent results. Much effort has been expended since first recognition of this insidious pleural cancer to elucidate the underlying cause and optimal treatment strategy. Despite recent breakthroughs, the principal barrier to achieving a cure rests with the propensity for disease recurrence in the ipsilateral hemithorax. Despite these limitations, however, the results hold promise for improved survival with further refinement in patient selection and targeted therapy. Other approaches to multimodality treatment have capitalized on an array of innovative technologies in search of the silver bullet strategy that will ultimately undermine the biological behavior demonstrated by MPM. These range from the use of different means of radiation delivery, biological agents, virally mediated gene therapy, photodynamic therapy, and immunotherapy. Additionally, studies using gene ratios will yield more accurate means by which to diagnose, distinguish prognosticators, and more selectively assign patients to aggressive treatments. In light of the current worldwide epidemic, the lessons learned over the past several decades serve as a humbling reminder of the treatment barriers that remain.

Extrathoracic Mesothelial Proliferations and Their Mimics

Mesothelial proliferations, either reactive or neoplastic in nature, often pose difficult diagnostic dilemmas. Electron microscopy continues to be a gold standard in the identification of mesothelial differentiation. However, it is very common to apply long panels of antibodies for that purpose. In most cases, light microscopy and immunohistochemistry will solve the problem. However, the definitive, specific, and sensitive immunohistochemical marker is still lacking. This is particularly true in peritoneal and testicular mesothelial tumors, in which common embryologic origin with epithelial elements results in overlapping immunohistochemistry and morphology. The particularities of peritoneal and testicular mesothelial proliferations, and the main tumors that may mimic them in these sites, as well as the value and limitations of immunohistochemistry and electron microscopy in their differential diagnosis are the subject of this review.

Use of mesothelin as a marker for mesothelial cells in cytologic specimens

Immunocytochemistry is often employed for the distinction between mesothelial cells and adenocarcinoma. Mesothelin has recently been reported to be expressed in reactive mesothelial cells and epithelioid mesotheliomas. The objective of this study is to determine the utility of mesothelin as marker for mesothelial cells in cytologic preparations. Thirty cell blocks were retrieved from the archives and immunostained with monoclonal antibody directed against mesothelin and calretinin. Heat-induced epitope retrieval technique was employed, and the immunostaining was accomplished using an automated stainer. These tissue blocks were from 35 patients (17 females and 18 males) with a median age of 64 years. Nine were benign effusions, 11 mesotheliomas, and 18 metastatic adenocarcinomas. The presence of any immunoreactivity, irrespective of level of intensity or percentage of cells, was considered positive for mesothelin expression. Follow up included correlation with pathology materials obtained at surgery and review of medical records. Mesothelin staining was positive in 7/9 benign cases, 8/11 mesotheliomas, and 8/18 adenocarcinomas. The difference of mesothelin expression between mesothelial cells and adenocarcinoma was statistically significant. For calretinin, all cases, except 2 malignant mesotheliomas and 3 adenocarcinomas, showed positive staining with calretinin. As a marker for mesothelial cells, the sensitivity and specificity of mesothelin were 73% and 55%, respectively, and the sensitivity and specificity of calretinin were 95% and 86%, respectively. Therefore, mesothelin is not a sensitive or a specific marker for mesothelial cells in cytologic specimens when compared with calretinin.

Differentiation of mesothelioma from adenocarcinoma in serous effusions: The role of hyaluronic acid and CD44 localization

Differentiating cells of mesothelial origin from adenocarcinoma (ACA) based on morphology alone can be a diagnostic challenge, especially in cytological specimens. Malignant mesothelioma (MM) is characterized by accumulation of abundant intracellular hyaluronic acid (HA), a feature that is not reported in ACA. The purpose of this study was to evaluate the significance of cellular HA using an HA-specific binding peptide (HABP) and the expression of its principal receptor, the standard CD44 molecule (CD44S). Archival paraffin-embedded cell blocks of serous fluids from 28 cases of reactive mesothelial cells, 14 cases of MM, 20 cases of metastatic ovarian carcinomas, 17 cases of metastatic breast carcinomas, 12 cases of metastatic lung ACA, and 12 cases of metastatic gastrointestinal ACA were stained with HA using a biotinylated HABP and CD44S. Positive staining was defined as droplet to diffuse cytoplasmic staining for HA and uniform membranous staining for CD44S. All MMs and 93% (26/28) of the benign mesothelial cells were positive for intracytoplasmic HA vs. none of ACAs. CD44S was expressed in 100% (28/28) of mesothelial hyperplesia, 86% (12/14) of MMs, 70% (14/20) of ovarian carcinomas, 29% (5/17) of breast carcinomas, 25% (3/12) of gastrointestinal ACAs, and 8% (1/12) of lung ACAs. In MM and reactive mesothelial cells, CD44S stained cell membranes diffusely with highlights on the villous surfaces and in ACA it was focal and confined to cell membranes. Immunostaining with HA is a reliable marker that can distinguish between cells of mesothelial origin (reactive mesothelial cells and MM) and ACA. The CD44S staining pattern of cells of mesothelial origin is of diagnostic significance. CD44 may prove useful in conjunction with other stains in the differential diagnosis of mesothelioma and ADA.

Preoperative assessment and therapeutic options for patients with malignant pleural mesothelioma

Prompt medical evaluation and aggressive treatment can lead to prolonged survival or successful palliation of symptoms for patients with malignant pleural mesothelioma, but the window for implementing treatment is short. Clinical recognition of the cancer is confounded by numerous factors, including long latency between exposure to asbestos and expression of the disease, nonspecific nature of the presenting symptoms, rarity of the disease, a lack of experience in clinical diagnosis, and rapidly deteriorating clinical course after diagnosis. Heightened clinical suspicion and proper patient selection through accurate staging and pathologic identification are paramount to defining and delivering therapy for this rare, lethal cancer.

Malignant pleural mesothelioma: overview of the North American and European experience

MPM is an uncommon disease with limited treatment options. Early diagnosis, a standardized staging system, early referral to centers experienced in MPM, and efforts to develop collaborative multicenter trials are essential to improving treatment for patients with MPM. Efforts to manage this malignancy, which is projected to peak in the twenty-first century, constitute an important international health concern, particularly because the use of asbestos, despite successful regulatory efforts in many parts of the world, continues unabated in others.

Serous effusions: diagnosis of malignancy beyond cytomorphology. An analytic review

In this brief review, the role of various ancillary techniques to detect malignancy in effusion fluid are evaluated and discussed. The data were collected from a large number of research articles published in various medical journals. The role of these techniques to increase the diagnostic accuracy in serous effusions is emphasised.

Immunohistochemical diagnosis of epithelioid mesotheliomas: a critical review of old markers, new markers

Numerous new immunohistochemical markers that can be used in the diagnosis of mesothelioma have recently become available. As a result, new panels of antibodies that could be useful for distinguishing between epithelioid mesotheliomas and adenocarcinomas have been proposed. However, great differences of opinion exist regarding the individual value of some of these markers, especially when compared with those whose value has already been established. This article provides a critical review of the currently available information on those markers that could be useful in the diagnosis of epithelioid mesotheliomas or whose utility remains controversial. A practical approach to the diagnosis of these tumors is also provided.

Use of a panel of markers in the differential diagnosis of adenocarcinoma and reactive mesothelial cells in fluid cytology

To evaluate the use of a panel of markers to differentiate adenocarcinoma and the reactive/inflammatory process in fluid cytology, we stained 29 formalin-fixed, paraffin-embedded cell blocks of effusion fluid from patients with metastatic adenocarcinoma and 24 cell blocks from patients with benign effusion with mucicarmine and antibodies to carcinoembryonic antigen (CEA), B72.3, and calretinin. Positive staining with CEA, B72.3, and mucicarmine was seen in 22 (76%), 20 (69%), and 18 (62%) adenocarcinoma cases, respectively. All except 1 adenocarcinoma was negative for calretinin. No benign cases were positive for B72.3 and mucicarmine. In 1 benign case, scattered epithelial cells demonstrated weak positivity for CEA. The majority of combinations were 100% specific for adenocarcinoma. The highest sensitivity (86%) for adenocarcinomas was achieved with the staining combination of negative for calretinin and positive for any adenocarcinoma marker (CEA, B72.3, or mucicarmine). The use of a panel of markers that recognize adenocarcinoma and mesothelial cells is useful in the differential diagnosis between metastatic adenocarcinoma and the reactive/inflammatory process. The profile of positive staining with at least one of the adenocarcinoma markers and negative calretinin staining is highly specific and sensitive for identifying adenocarcinoma in fluid cytology.

Use of E-cadherin and CD44 aids in the differentiation between reactive mesothelial cells and carcinoma cells in pelvic washings

BACKGROUND

The presence of malignant cells in peritoneal washings is an independent prognostic factor in the evaluation of gynecologic malignancies. The differentiation between reactive mesothelial cells and carcinoma cells can be a diagnostic challenge based on morphology alone. The expression of some cell adhesion molecules may be helpful in the differential diagnosis.

METHODS

To evaluate the specificity of 2 transmembrane cell adhesion proteins (E-cadherin and CD44) in the differentiation of mesothelial cells from carcinoma cells in pelvic washings, formalin fixed, paraffin embedded cell blocks of pelvic washings from 19 cases of metastatic ovarian adenocarcinoma and 16 cases of benign peritoneal washings were immunostained with monoclonal antibodies to E-cadherin and CD44. The staining patterns were evaluated blindly by three observers. Positive staining was defined as uniform membranous staining for each marker.

RESULTS

Fourteen benign peritoneal washings (87.5%) demonstrated immunoreactivity with anti-CD44. On the contrary, only four adenocarcinomas (21.1%) demonstrated anti-CD44 immunoreactivity. E-cadherin expression was identified in only 2 benign peritoneal washings (12.5%) whereas 16 adenocarcinomas (84.2%) strongly expressed E-cadherin. The differences in immunostaining for both CD44 and E-cadherin between benign and malignant peritoneal washings were statistically significant. The combination of positive staining for E-cadherin and negative staining for CD44 was 100% specific for metastatic adenocarcinoma, whereas a combination of negative staining for E-cadherin and positive staining for CD44 was 100% specific for reactive mesothelial cells.

CONCLUSIONS

Both E-cadherin and CD44 reliably distinguish reactive mesothelial cells from adenocarcinoma. The combination of E-cadherin/CD44 is highly specific and is a useful diagnostic adjunct with which to distinguish benign reactive mesothelial cells from adenocarcinoma in pelvic washings.

Malignant pleural mesothelioma presenting as spontaneous pneumothorax: a case series and review

BACKGROUND

Malignant pleural mesothelioma (MPM) is thought to arise from the mesothelial cells that line the pleural cavities. Most patients initially experience the insidious onset of chest pain or shortness of breath, and it rarely presents as spontaneous pneumothorax.

CASE REPORTS

We report four patients who presented in this manner. Three of the patients were exposed to asbestos directly or indirectly at shipyards during World War II; the fourth was exposed as an insulator's wife. Two of our cases were not recognized to have MPM on histologic examination at first thoracotomy and remained asymptomatic for 12 and 22 months, respectively. In none of the patients described herein, was spontaneous pneumothorax the cause of death.

CONCLUSIONS

Since many people were exposed to asbestos during and after World War II, spontaneous pneumothorax in a patient with the possibility of such exposure should raise the suspicion of malignant pleural mesothelioma.

Cytokeratin 8 immunostaining pattern and E-cadherin expression distinguish lobular from ductal breast carcinoma

Immunohistochemistry using antibodies to cytokeratin 8 can serve as a valuable diagnostic tool for the differentiation of lobular from ductal carcinomas of the breast. In contrast with ductal carcinomas, which exhibit a peripheral-predominant immunostaining pattern, adjacent tumor cells "molding" to each other, lobular carcinomas exhibit a ring-like perinuclear immunostaining pattern, creating a "bag of marbles" appearance with neighboring tumor cells. This immunostaining pattern is stable even in the tumors that otherwise do not exhibit characteristic histomorphologic features (i.e., solid or pleomorphic type of a lobular carcinoma) and tumors that mimic growth patterns characteristic of the respective other tumor type (i.e., targetoid or single-file growth pattern in a ductal carcinoma). Furthermore, we demonstrate that ductal carcinomas express E-cadherin in a similar peripheral-predominant immunostaining pattern (33/33 cases), while all 15 lobular carcinomas were negative for E-cadherin, suggesting a role for E-cadherin in the architectural organization of the cytoskeletal scaffolding within the tumor cells.

Calretinin staining pattern aids in the differentiation of mesothelioma from adenocarcinoma in serous effusions

BACKGROUND

The differentiation between malignant mesothelioma and adenocarcinoma based on morphology alone can be a diagnostic challenge. The majority of the available antibodies recognize molecules expressed by adenocarcinoma whereas to the authors' knowledge specific markers for mesothelial cells are lacking. Calretinin, a calcium-binding protein, has been reported to be a selective marker for mesothelioma and largely is absent from adenocarcinoma on histologic material. The results with cytologic preparations have been inconsistent.

METHODS

To evaluate the specificity of calretinin in differentiating mesothelioma from adenocarcinoma in cytologic preparations, 21 paraffin embedded cells blocks of serous effusions from 15 patients with metastatic adenocarcinoma and 16 cell blocks from 9 patients with malignant mesothelioma were stained with a monoclonal antibody against calretinin. The immunoreactivity was evaluated blindly by two observers. Positive staining was defined as nuclear and cytoplasmic staining with or without intense membranous decoration. The former resulted in a characteristic "fried egg" appearance.

RESULTS

Calretinin staining was positive in all but 2 cases of mesothelioma (14 of 16 cases; 87.5%). The latter contained predominantly spindle-shaped neoplastic mesothelial cells in the cell block preparations. All adenocarcinoma specimens were classified as negative for calretinin staining; 9 (42.9%) lacked any immunoreactivity and 12 (57.1%) showed weak, sparse, coarse, granular cytoplasmic staining without nuclear or membranous staining. Benign reactive mesothelial cells, when observed in association with adenocarcinoma, also showed the characteristic "fried egg" appearance. The difference in the staining pattern of calretinin between cells of mesothelial origin and adenocarcinoma cells was statistically significant.

CONCLUSIONS

Calretinin is a useful marker in differentiating mesothelioma of the epithelial type from adenocarcinoma in serous effusions. The "fried-egg" appearance or cytoplasmic and nuclear staining pattern is characteristic of cells of mesothelial origin.

E-cadherin expression is a sensitive and specific method for detection of carcinoma cells in fluid specimens

The distinction between reactive mesothelial cells and carcinoma in pleural, peritoneal, and pericardial fluids is often difficult. We and others previously showed that E-cadherin, an epithelial-specific adhesion protein, can be useful for this distinction. In this study we tested the sensitivity and specificity of E-cadherin compared to, and in combination with, conventional cytology for assessment of carcinoma in fluids. Cytyc ThinPreptrade mark slides (Marlborough, MA) from 102 sequential fluids were evaluated for E-cadherin expression by routine immunologic techniques. No evidence of E-cadherin staining was seen in 71 cases, while 31 showed unequivocally positive staining. Sensitivity and specificity were independently determined for E-cadherin alone (72% and 97%, respectively), cytomorphology alone (62% and 100%, respectively), and both together (92% and 100%, respectively). We conclude that assessment of E-cadherin expression has sensitivity and specificity comparable to, or better than, conventional cytomorphology. If both cytomorphology and E-cadherin are used together, a definitive and correct diagnosis could have been made on nearly every case in this study.

NCAM (neural cell adhesion molecules) expression in malignant mesotheliomas

Neural cell adhesion molecules (NCAM) are adhesion molecules expressed by neural and neuroendocrine tumors and a few biphasic tumors such as synovialosarcomas and breast phyllode tumors. To investigate NCAM expression in mesotheliomas, we studied 26 cases of epithelioid (n = 12), biphasic (n = 11), and sarcomatoid (n = 3) malignant mesotheliomas (MM), in comparison with normal mesothelium, and 50 primary non-small cell lung carcinomas (NSCLC) (25 adenocarcinomas [ADC] and 25 squamous cell carcinomas [SCC]), using electron microscopy as a gold standard for recognition of MM. NCAM reactivity using 123C3 antibody was compared with that of NE markers such as chromogranin A and synaptophysin. Although normal mesothelium remains negative, NCAM was expressed in 19 of 26 MM (73%) with a membranous staining on frozen or paraffin sections. In 6 of 12 epithelioid MM, the tumor cells expressed NCAM, whereas in 5 cases stromal fibroblasts showed a strong but focal staining. In 11 biphasic MM, 4 presented an NCAM reactivity of both epithelioid and spindle cell components, whereas in 7, only fusiform component was NCAM positive. Two of 3 sarcomatoid MM showed an NCAM expression. Chromogranin expression was never seen, whereas synaptophysin was noticed in 2 cases. No case of NSCLC showed membranous 123C3 staining, whereas 2 ADC weakly expressed synaptophysin. We conclude that NCAM expression in MM is reminiscent of its expression in mesoderm during fetal life and consistent with that reported in other biphasic tumors. These data show that NCAM expression occurs in 73% of MM, highly exceeding that observed in lung cancer.

MOC-31 aids in the differentiation between adenocarcinoma and reactive mesothelial cells

BACKGROUND

Evaluation of effusion specimens for the presence of adenocarcinoma often is complicated by the presence of reactive mesothelial cells that can mimic adenocarcinoma. Ancillary studies, in particular immunohistochemistry, can be helpful in making this distinction. MOC-31 is an antibody that recently was reported to be useful in distinguishing adenocarcinoma from mesothelioma in tissue specimens. In this study we examined the utility of this antibody in pleural effusions.

METHODS

Eighty-nine archival, formalin fixed, paraffin embedded cell blocks representing 59 adenocarcinomas, 12 other neoplasms (including 6 mesotheliomas), and 18 reactive effusions were retrieved. After protease digestion, recut slides were immunostained with the MOC-31 antibody utilizing a modified avidin-biotin complex technique. Only membrane-based reactivity was considered as positive.

RESULTS

In two adenocarcinomas there was insufficient material remaining in the cell block. Among the 57 remaining cases, reactivity was observed in 54 cases. Reactivity also was observed in one of six mesotheliomas and one small cell carcinoma. The remaining cases, including all 18 reactive effusions, were nonreactive. In distinguishing adenocarcinoma from reactive mesothelial cells, the presence of MOC-31 reactivity was found to be 95% sensitive and 100% specific with a positive predictive value of 100% and a negative predictive value of 95%.

CONCLUSIONS

MOC-31 is useful in differentiating between adenocarcinoma and reactive mesothelial cells in pleural effusion specimens. Cancer (Cancer Cytopathol)

Cytokeratin markers in malignant pleural mesothelioma

Previously available serum tumor markers had a low clinical value in malignant pleural mesothelioma (MPM). The recently developed tissue polypeptide-specific antigen (TPS) and CYFRA 21-1 assays identify the soluble cytokeratin 18 and 19 fragments, respectively. In MPM these cytokeratins are expressed and may therefore be used as serum tumor markers. In this preliminary study, TPS and CYFRA 21-1 assays were evaluated to determine their potential for management of patients with MPM. Carcinoembryonic antigen (CEA) was evaluated as an additional marker. The study group consisted of 95 patients with benign lung and pleural diseases (BLPD), 14 patients with MPM, 41 patients with adenocarcinoma of lung (AC), and 40 patients with squamous cell carcinoma of lung (SQC). The utilized cutoff points corresponded to a 95% specificity for patients with BLPD. In MPM, TPS showed greater sensitivity (64.3%) than CYFRA 21-1 (50.0%), while CEA showed no sensitivity. In SQC, the marker CYFRA 21-1 had the highest sensitivity (52.5%), whereas in AC the most sensitive marker was CEA (56.1%). Significantly lower levels of CEA were found in MPM compared with BLPD (p < 0.001) or AC and SQC (p < 0.0001). Conversely, TPS levels in MPM were significantly higher than in SQC (p < 0.05). Close correlation of various individual pretreatment marker levels was observed only between TPS and CYFRA 21-1, both in MPM (r = 0.84; p < 0.001) and in non-small cell lung cancer (NSCLC) (r = 0.71; p < 0.001). In serial determinations of the markers during chemotherapy of MPM (n = 10), TPS and CYFRA 21-1 were shown to demonstrate more or less the same pattern of reactivity, although the changes in the TPS levels better reflected the clinical response to therapy. In conclusion, TPS seems to be a more sensitive marker than CYFRA 21-1.

Utility of the antibodies CA 19-9, HBME-1, and thrombomodulin in the diagnosis of malignant mesothelioma and adenocarcinoma in cytology

BACKGROUND

The distinction between malignant mesothelioma (MM) and adenocarcinoma (ACA) in cytologic specimens frequently is difficult, often requiring immunocytochemistry to support the diagnosis. Recent reports have proposed the utilization of antibodies to mesothelial cell clone HBME-1 and thrombomodulin (TM), because they are immunoreactive in MM and less commonly reactive in ACA. Immunoreactivity for the monoclonal antibody CA 19-9 has been observed in many ACAs and reportedly is absent in MM.

METHODS

In this study, immunostaining was performed on formalin fixed, paraffin embedded cell blocks from effusions or fine-needle aspirations using the avidin-biotin-peroxidase method. Thirty-eight MMs and 49 ACAs were tested using antibodies to CA 19-9, HBME-1, and TM.

RESULTS

Anti-CA 19-9 stained only 1 of the 37 cases of MM tested (3%), but stained 24 of the 49 cases of ACA (49%). Anti-HBME-1 stained 34 of 38 cases of MM (89%), and 28 of 43 cases of ACA tested (65%). Anti-TM stained 24 of 36 cases of MM (67%), and 21 of 40 cases of ACA tested (53%).

CONCLUSIONS

CA 19-9 has utility as part of an immunocytochemical panel for distinguishing ACA from MM, because a positive staining reaction would make the diagnosis of MM unlikely. Although HBME-1 and TM can identify MM positively, each frequently is detected in ACA, thus limiting the utility of these antibodies in cytologic specimens.

The value of antibodies 44-3A6, SM3, HBME-1, and thrombomodulin in differentiating epithelial pleural mesothelioma from lung adenocarcinoma: a comparative study with other commonly used antibodies

The distinction between pleural mesothelioma and peripheral pulmonary adenocarcinoma involving the pleura continues to be a diagnostic problem in surgical pathology. In recent years, the use of various immunohistochemical markers to facilitate this differential diagnosis has become common. In this study, the value of monoclonal antibodies 44-3A6, SM3, HBME-1, and thrombomodulin is compared in the differentiation of these conditions. Fifteen (68.2%) of 22, and 10 (52.6%) of 19 mesotheliomas stained positively with 44-3A6 and SM3, respectively, whereas all 23 (100%) adenocarcinomas reacted with both antibodies. Sixteen (80%) of 20 mesotheliomas and 14 (63.6%) of 22 lung adenocarcinomas reacted with HBME-1, whereas 16 (80%) of 20 mesotheliomas and only three (11.1%) of 27 adenocarcinomas were positive for thrombomodulin. Because thrombomodulin was expressed in most mesotheliomas but in only a few lung adenocarcinomas, this marker may have some diagnostic value when it is included in the standard immunohistochemical panel of markers used in the evaluation of mesotheliomas, especially when a positive marker for mesothelioma is needed. Antibodies 44-3A6, SM3, and HBME-1 have no practical value in discriminating epithelial pleural mesothelioma from lung adenocarcinoma.

Optimization of a battery using nine immunocytochemical variables for distinguishing between epithelial mesothelioma and adenocarcinoma

A battery of immunocytochemical analyses, previously established to distinguish between malignant mesothelioma and metastatic adenocarcinoma, was extended by analysing the same cases with three other commercially available antibodies. Altogether, 11 antibodies were studied in mesotheliomas diagnosed by other means, using 14 different immunocytochemical parameters. Logistic regression analysis indicated that the following parameters were of importance for this diagnostic problem: vimentin reactivity in epithelial cells (1), cytokeratin (CAM 5.2) reactivity in spindle-shaped (fibrous) cells (2), cell membrane-associated reactivity of EMA (3), HBME-1 (4) and thrombomodulin (5), and absence of reactivity to CEA (6), CD15 (7), BerEp4 (8) and Sialyl-TN (9). The analysis gave an algorithm with which a specific diagnosis of mesothelioma could be made in 80% of the cases-i.e., some improvement compared to the 55% sensitivity using the previous battery.

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.

HBME-1 and antithrombomodulin in the differential diagnosis of malignant mesothelioma of pleura

AIMS

To determine the usefulness of antibodies HBME-1 and antithrombomodulin in the differential diagnosis of malignant mesothelioma of the pleura.

METHODS

Using microwave antigen retrieval and streptavidin-biotin complex horseradish peroxidase immunohistochemistry the above antibodies were used to stain sections of 57 malignant mesotheliomas, 17 reactive pleural hyperplasias, 23 cases of carcinoma metastatic in pleura, 20 primary ovarian cell carcinomas, and 20 primary renal cell carcinomas.

RESULTS

Eighty six per cent of mesotheliomas and 82% of reactive mesothelial hyperplasias stained strongly with HBME-1. However, 48% of carcinomas metastatic to pleura also stained, as did all serous ovarian carcinomas. Seventy two per cent of mesotheliomas and 24% of reactive mesothelial hyperplasias stained strongly with the antithrombomodulin antibody; 86% and 88%, respectively, of these cases showed staining of any type. While 26% of metastatic carcinomas showed some staining with antithrombomodulin, only one third of these (9%) showed strong, yet focal, staining. Of 40 ovarian and renal carcinomas only two (5%) showed any staining with antithrombomodulin.

CONCLUSIONS

HBME-1, although a sensitive mesothelial marker, is not sufficiently specific to be useful diagnostically, as almost half of carcinomas metastatic to pleura also stained positive. Antithrombomodulin is also a sensitive mesothelial marker and is sufficiently specific to be a useful discriminator, positively identifying, in appropriate circumstances, the mesothelial nature of a cell population.

Complementary value of five carcinoma markers for the diagnosis of malignant mesothelioma, adenocarcinoma metastasis, and reactive mesothelium in serous effusions

Cytological slides of serous fluids of 41 malignant mesotheliomas, 88 metastatic adenocarcinomas, and 25 reactive effusions were immunostained with the antibodies anti-CEA, MOC-31, Leu-M1, Ber-EP4, and B72.3. Most mesotheliomas and all reactive fluids failed to stain with these antibodies. The sensitivity of the five markers to detect carcinoma cells differed remarkably. Especially MOC-31, Ber-EP4, and B72.3 stained with a high number of carcinoma cases and the complemetary value of Ber-EP4 and B72.3 to immunostain carcinoma cells was impressive: 94% of the metastatic adenocarcinoma cases reacted with Ber-EP4 or B72.3 in contrast to 1 of 41 malignant mesotheliomas.

An autopsy case of diffuse malignant mesothelioma of the pericardium

A report is presented of an autopsy case of a 71-year-old Japanese man with a diffuse malignant epithelial mesothelioma of the pericardium with massive pericardial effusion and a thickened pericardium. He had no history of exposure to asbestos. He suffered severe heart failure and later died. Autopsy revealed that the tumor had developed over the pericardium. Microscopically, the tumor cells were arranged in an epithelial form, and histochemically, the cytoplasm of these cells contained glycogen and hyaluronic acid. The tumor tissue showed immunohistochemical positivity for cytokeratin, epithelial membrane antigen, vimentin, cancer antigen 125, thrombomodulin, mesothelial antigen, muscle actin and human milk fat globule. In contrast, all the tumor cells were negative for human carcinoembryonic antigen and epithelial antigen. Ultrastructurally, the tumor cells had long, thin microvilli, abundant intermediate filaments, intracytoplasmic lumina and long desmosomes. It is considered that the patient had a typical malignant epithelial mesothelioma of the pericardium.

Pleural mesothelioma: an approach to diagnostic problems

In the 1960s, a close relationship between heavy exposures to crocidolite asbestos and mesothelioma was established. The debate on the diagnosis of mesothelioma became complicated because of the possibility of litigation. Well differentiated mesothelioma cells are mucicarmine negative but alcian blue and periodic acid-Schiff (PAS) positive, which are removed by hyaluronidase and diastase digestion. By electron microscopy (EM), they show bush-like elongated, slender, and branching microvilli. By immunohistochemistry they express both keratin and vimentin but not carcinoembryonic antigenicity (CEA), B72.3, Ber-EP4, and Leu-M1. In poorly differentiated mesotheliomas, chromosomal and molecular biological alterations are common and complex but these alterations also overlap with that of poorly differentiated tumours of the lung and other organs. A poorly differentiated pleural tumour is most likely metastatic and needs good team work to locate the primary site. The diagnosis of a mesothelioma and asbestosis should be established separately. Future studies will be focused less on the phenotypic differences but more on the broad molecular and multi-phasic mechanisms of carcinogenesis, irrespective of the aetiological agents, in poorly differentiated tumours.

Mesothelioma-binding antibodies: thrombomodulin, OV 632 and HBME-1 and their use in the diagnosis of malignant mesothelioma

The aim of this study was to examine the expression of three putative mesothelioma-binding antibodies, thrombomodulin, OV 632 and HBME-1 in 42 malignant mesotheliomas (27 pleural and 15 peritoneal) and 32 pulmonary adenocarcinomas. Evaluation of their use in differentiating between the mesotheliomas and pulmonary adenocarcinomas was assessed. Thrombomodulin was expressed by 22 of 42 (52%) mesotheliomas but was seen in eight of 12 pure epithelial-type mesotheliomas of the pleura and in all four papillary epithelial peritoneal mesotheliomas. For pure epithelial mesotheliomas thrombomodulin was 75% sensitive. Only two of 32 pulmonary adenocarcinomas were immunoreactive yielding a 94% specificity for thrombomodulin. In comparison, OV 632 and HBME-1 showed 67% and 62% antibody sensitivity, respectively, for malignant mesothelioma but this was accompanied by low specificity (OV 632, 37%; HBME-1, 28%). Both OV 632 and HBME-1 are considered unsuitable for use in differentiating between mesotheliomas and pulmonary adenocarcinomas. We advocate the use of thrombomodulin as a mesothelioma-binding antibody in the standard panel of antibodies used in the evaluation of malignant mesothelioma.

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)

Utility of cytokeratin 20 in identifying the origin of metastatic carcinomas in effusions

Using a commercially available monoclonal antibody (Ks20.1) and the avidin-biotin peroxidase method on cytospins and cell blocks, we analyzed cytokeratin (CK) 20 expression in 169 serous effusions. Cytoplasmic staining was observed in 44/151 malignant fluids. Colon, gastric, and pancreatic adenocarcinomas and mucinous ovarian tumors were most frequently positive. Single cases of transitional-cell and squamous cell carcinomas were reactive as well. Lung and breast cancers were mostly negative. Nonmucinous ovarian tumors were invariably unlabeled as were mesotheliomas and normal mesothelial cells. The study shows that CK 20 is valuable in distinguishing tumor cell origin in effusions. In particular, it identifies a set of carcinomas with the majority arising from the gastrointestinal tract, and represents a highly characteristic marker for colorectal cancer.

Immunocytochemical characterization of malignant mesothelioma and carcinoma metastatic to the pleura: IOB3--a new tumor marker

We have tried to find a reliable panel of markers that would allow distinction between mesotheliomas and carcinomas metastatic to the pleura. In a prospective study, we evaluated 54 pleural effusions: In 27 of the patients, a diagnosis of histologically proven metastatic carcinoma was subsequently established, 7 patients had biopsy-proven malignant mesotheliomas and 20 had benign, reactive effusions whose benign etiologies were established by more than 2 years clinical follow-up. The MAb (monoclonal antibody) IOB3 proved to be diagnostic for carcinomas in all 27 cases (100%), whereas CEA (carcinoembryonic antigen) expression was found in only 22 out of 27 (81%). None of the malignant mesotheliomas, nor benign reactive mesothelial cells reacted with these two markers. All carcinomas, as well as one malignant mesothelioma, reacted with the MAb HEA125. Antibodies against 12 single cytokeratins, vimentin, and EMA (epithelial membrane antigen) were not helpful in the differentiation between malignant mesotheliomas and malignant carcinomatous pleural effusions. We conclude that adding the antibody IOB3 to the CEA assay should allow a reliable differentiation between these two entities.

Differentiation of adenocarcinoma of the lung and malignant mesothelioma: predictive value and reproducibility of immunoreactive antibodies

A panel of antibodies against keratins, epithelial membrane antigen (EMA), epithelial antigen (Ber-EP4), carcinoembryonic antigen (CEA), tumour-associated glycoprotein (B72.3), vimentin and LeuM1 was applied to sections of adenocarcinoma of the lung and malignant mesothelioma in a randomized design. The proportion of stained tumour cells within each section was estimated independently in five categories by three pathologists (no positive tumour cells, 1-10%, 11-33%, 34-66% and more than 67% positive tumour cells). The kappa values representing the chance corrected interobserver agreement for the different antibodies in such a five group assessment were between 0.38 and 0.72. In two group assessment the kappa values were between 0.53 and 0.94. Nosological sensitivity and nosological specificity were calculated for all antibodies, and diagnostic sensitivity and diagnostic specificity (predictive values) were calculated for the Ber-EP4, CEA, B72.3, LeuM1 and vimentin. The difference between nosological sensitivity and nosologic specificity and the clinically relevant predictive values of positive and negative tests were demonstrated. In respect of the reproducibility and the diagnostic power defined by the predictive values, we demonstrated that a panel of antibodies, including CEA, Ber-EP4 and B72.3 and, to a lesser degree, LeuM1 and vimentin is applicable for the histopathological distinction between adenocarcinoma of the lung and malignant mesotheliomas. Before introduction of new diagnostic tests, including new antibodies, the prevalence of the tested tumours should be estimated. Nosological sensitivity and nosological specificity should be converted to predictive values.

Biologic Charachterization of Pleural Metastases from Lung Adenocarcinoma: Description of the New DV90 Cell Line

Aims and background

The characterization of pleural metastases from lung adenocarcinoma is often limited to single biologic features.

Methods

The present paper describes the cellular kinetic parameters, as well as immunocytochemical, ultrastructural and genetic characteristics of the new DV90 cell line, established from the pleural effusion of a stage IV lung adenocarcinoma.

Results

The cell line has a diploid DNA content, a doubling time of 24 h and 7% cloning efficiency, it is tumorigenic in nude mice. Ultrastructural investigation revealed the typical features of lung adenocarcinoma; the diagnosis was confirmed by its immunohistochemical reactivity with a panel of monoclonal antibodies specifically capable of identifying adenocarcinoma cells. Genetic analysis revealed a 46 X, –Y, +8, der (6)t(6?)(q27;?) karyotype and hyperexpression of the protein codified by genes Her2/Neu and p53.

Conclusion

The importance of multidisciplinary biologic characterization in identifying the origin and biological behavior of pleural metastases deriving from lung adenocarcinoma is discussed.

Markers for metastatic adenocarcinoma in serous effusion specimens

A variety of stains have been proposed as useful adjuncts to the morphologic diagnosis of serous effusion specimens. This study evaluates the sensitivity and specificity of nine stains for the detection of metastatic adenocarcinoma in effusions. Mucin cytochemistry with the Periodic acid-Schiff reaction after diastase digestion (PASd) and the mucicarmine method, as well as immunochemical staining for five glycoprotein antigens, was undertaken on 153 effusion specimens with histological and/or clinically confirmed diagnoses. Immunochemical stains included three antibodies to CEA (Dako polyclonal, 4E7 and A5B7) and antibodies to HEA (Ber-EP4), TAG 72 (B72.3), CD15 (LeuM1) and Epithelial membrane antigen (EMA) were evaluated. The sensitivity of the stains for adenocarcinoma (102 cases) was: PASd 37%; mucicarmine 24%; polyclonal anti-CEA 69%; 4E7 52%; A5B7 21%; EMA 91%; B72.3 44%; Ber-EP4 32%; LeuM1 24%. With the exception of EMA, none of the stains reacted with any cases of benign mesothelial cells (11 cases), reactive mesothelial cells (34 cases), or with six cases of mesothelioma. However, EMA staining was present in two cases (6%) of reactive mesothelial cells and all cases of mesothelioma. The optimal combination of stains for use in a panel was polyclonal anti-CEA/B72.3/PASd. Combined results from these three stains yielded a sensitivity of 83% for adenocarcinoma with no false positive results. It is concluded that special staining may provide valuable information to assist in the classification of difficult effusion cases.

Immunocytochemical typification of mesothelial cells in effusions: in vivo and in vitro models

We have performed immunocytochemical, immunoelectron microscopy, Western blot, and culture techniques using monoclonal antibodies against cytokeratin, vimentin, and desmin on 17 benign and 20 malignant effusions of pleural and ascitic origin. Triple coexpression of these three antigens was observed in benign reactive mesothelial cells as well as in one case of mesothelioma. All metastatic adenocarcinoma cells were consistently negative to desmin and positive to cytokeratin and vimentin. Present results were helpful to distinguish reactive and malignant mesothelioma from metastatic carcinoma cells in effusions.

Immunocytochemical staining of serous effusions: an additional method in the routine cytology practice?

In a consecutive and prospective cytomorphologic and immunocytochemical study we have examined 100 serous fluids with a panel of antibodies. Three different immunocytochemical patterns of staining were recognized: (i) a benign profile showing no Ber-EP4 or CEA-positive cells; (ii) a malignant profile with Ber-EP4 and strongly EMA-positive epithelial cells; and (iii) a malignant profile in which mesothelial cells were strongly positive for EMA. By applying these profiles the number of malignant cases recognized increased from 19 to 38. All cytomorphologic malignant fluids showed a malignant profile, but in two cases a malignant epithelial profile was found in patients without otherwise proven malignant disease (false positive staining). Immunocytochemistry with anti-Ber-EP4 and anti-EMA can be recommended as a routine procedure, but the marker result should always be correlated with cytomorphology, eventual histologic data and clinical records.

Immunocytochemical characterization of cell lines from human malignant mesothelioma: characterization of human mesothelioma cell lines by immunocytochemistry with a panel of monoclonal antibodies

A panel of nine monoclonal antibodies was used to characterize human mesothelioma cell lines that we established from human malignant mesothelioma. The antigens detected were cytokeratin, vimentin, epithelial membrane antigen, carcinoembryonic antigen, Leu-M1 (CD15), desmin, factor VIII-related antigen (von Willebrand factor antigen), OV632, and ME1, a specific monoclonal antibody directed against human malignant mesothelioma. The technique used was the alkaline phosphatase anti-alkaline phosphatase method. All 30 cell lines, either epithelial, sarcomatous, or mixed, showed strong reactivity with cytokeratin and vimentin antibodies. None of the cell lines demonstrated any reactivity with carcinoembryonic antigen, Leu-M1, or factor VIII antibodies; moreover, all of 22 cell lines studied were positive for ME1 antibody and 10 of 12 cell lines studied were positive for OV632. Some interesting features were noted: only two of the 30 cell lines presented a weak positive staining with epithelial membrane antigen, and nine of 19 cell lines tested demonstrated a cytoplasmic staining pattern with desmin antibody. These results show that established human mesothelioma cell lines still possess the immunocytochemical characteristics that are basically consistent with the immunohistochemical features described in tumor tissues of malignant mesothelioma. These characteristics can be used to identify the mesothelioma cells grown from human malignant mesothelioma. Hence, the mesothelioma cell lines will provide a useful tool for the investigation of the cell biology of the tumor and the mechanisms of mesothelial cell transformation, as well as the in vitro evaluation of the effects of some drugs in order to develop new therapies for malignant mesothelioma.

Monoclonal antibody Ber-EP4: its use in the differential diagnosis of malignant mesothelioma and carcinoma in cell blocks of malignant effusions and FNA specimens

Formol sublimate-fixed cell blocks derived from 129 malignant pleural (and some peritoneal) effusions, 8 benign effusions with reactive mesothelial cells, and 23 FNA specimens, were immunostained with monoclonal antibody Ber-EP4 to assess its ability to distinguish malignant mesothelioma (MM) from carcinoma. Only 2 of 44 (4%) well-characterized MM were Ber-EP4+, while none of 8 benign mesothelial proliferations reacted with the antibody. Fifty-seven percent of 23 pulmonary adenocarcinomas (AC) and 60% of 43 pulmonary carcinomas of all other histological types were Ber-EP4+. Of 40 metastatic AC originating from breast, gastrointestinal tract, ovary, endometrium, and kidney, 80% were Ber-EP4+. The predictive value of positive Ber-EP4 staining in distinguishing AC from MM was 96%. The predictive value of a negative Ber-EP4 in excluding MM was 70%, when the differential diagnosis was adenocarcinoma. These results suggest that Ber-EP4 is helpful in differentiating MM and AC if used together with other discriminating antibodies.

Comparison of monoclonal antibodies AUA1 and BER EP4 with anti-CEA for detecting carcinoma cells in serous effusions and distinguishing them from mesothelial cells

Commercially available monoclonal antibodies AUA1, BER EP4 and carcinoembryonic antigen (CEA) were applied to cell blocks from 95 serous effusions. AUA1 and BER EP4 were reactive with 89% of effusions known to contain carcinoma cells, and anti-CEA with 71%. They also reacted with cells in two effusions from patients with malignant disease which were regarded as negative on conventional cytological examination of Papanicolaou-stained smears. They were negative in all but one of the benign effusions. Using all three antibodies, 95% of effusions containing carcinoma cells were detected. Use of these antibodies could improve the cytological diagnosis of serous effusions.

Improvement of the diagnosis of the cause of pleural effusion in patients with lung cancer by simultaneous quantification of carcinoembryonic antigen (CEA) and neuron-specific enolase (NSE) pleural levels

Carcinoembryonic antigen (CEA) and neuron-specific enolase (NSE) level determinations were carried out by radioimmunoassay in pleural fluid and plasma samples obtained from 24 patients with malignant pleural effusions and 18 patients with non-malignant pleural effusions, and compared to cytological and pathological results. Using a pathological cut-off level of 25 ng/ml for CEA and 8 ng/ml for NSE, we demonstrated that, in the diagnosis of the malignant nature of pleural effusions, the simultaneous quantification of CEA and NSE in pleural fluid possesses better discriminative values than the simultaneous quantification of both markers in plasma or the separate quantification of each marker, in pleural fluid and in plasma.

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.

The utility of ancillary techniques in effusion cytology

We believe that, in general, immunocytochemical studies when used as a panel are the most helpful of the ancillary techniques in the workup of a difficult effusion cytology case. Routine histochemical stains for mucin should also be employed due to their low cost and simplicity, but suffer from lack of sensitivity and specificity. EM examination is especially helpful in the differentiation of metastatic carcinoma from mesothelioma, but lacks specificity due to overlapping ultrastructural features, and is both costly and labor intensive. Immunophenotyping by flow cytometry is useful in the workup of problematic lymphoid proliferations, but DNA analysis by flow cytometry is not useful as a screening technique. Fortunately, most effusion cytology cases will not need the use of ancillary studies, since the diagnosis will be accurately rendered based on the cytomorphologic findings. However, occasional cases will benefit from the use of specific ancillary studies, which can aid in making an accurate, specific, and rapid diagnosis in an otherwise challenging case.