Lupus erythematosus cell in body fluids: A case report and review of literature.

The diagnosis of systemic lupus erythematosus (SLE) has undergone radical change after the development of serological techniques. The in vitro demonstration of lupus erythematosus (LE) cell has less significance for the diagnosis of SLE in the present scenario. Although over the years, the spontaneous in vivo occurrence of LE cell in numerous body fluids as an initial presentation of SLE has been documented. The report of the presence of the LE cell can not only aid in the further workup of the patient but also suggest the involvement of a particular organ or body cavities by SLE. The morphology and mimickers of the LE cell should be cogitated and meticulous search of such cells should play an important role in the evaluation of body fluids. In our case, the patient presented at emergency with pericardial tamponade and cytological evaluation of the pericardial fluid demonstrated in vivo presence of LE cells. The serological work-up then confirmed the case to be SLE. This report and review of literature wish to highlight the fact that this cell still plays a significant role even in the era of immunoassays.

Morphological characterization and molecular profiling of malignant pericardial effusion in patients with pulmonary adenocarcinoma.

CONTEXT: Malignant pericardial effusions (MPCEs) is a common complication observed in advanced pulmonary adenocarcinoma. In such cases, investigating molecular alterations can have significant therapeutic implication in determining anticancer drugs. AIM: The objective was to evaluate the significance of cell block technique in the diagnosis of MPCE and further investigate the morphological and molecular profiles of MPCE in patients with pulmonary adenocarcinoma. SETTING AND DESIGN: Cytopathological and molecular profiles of 19 MPCE cases in patients with pulmonary adenocarcinoma were retrospectively analyzed. The control group consisted of 14 malignant pleural effusion (MPE) cases in patients with pulmonary adenocarcinoma. MATERIALS AND METHODS: Anaplastic lymphoma kinase (ALK) and tyrosine-protein kinase Met (C-MET) expression was evaluated by fluorescence in situ hybridization (FISH). Epithelial growth factor receptor (EGFR) and K-Ras (KRAS) mutations were detected by ARMS real-time polymerase chain reaction (RT-PCR). STATISTICAL ANALYSIS USED: Associations between MPCE and MPE were analyzed using Fisher's exact test. RESULTS: MPCE was found to have micropapillary and solid pattern predominant with mucin secretion compared to acinar patterns, as seen in MPE. Seventeen MPCE cases (89.5%) and all MPE cases (100%) underwent molecular analysis. Mutations in EGFR and KRAS, ALK rearrangement, and C-MET amplification were observed in MPCE and MPE with statistical differences. Additionally, two MPCE cases demonstrated EGFR T790M mutation and multiple insertions at L858. CONCLUSIONS: MPCE shows micropapillary and solid cytological patterns predominant with mucin secretion. MPCE are suitable to analyze oncogenic mutations and to develop targeted therapy for patients with pulmonary adenocarcinoma. Further molecular investigations may reveal novel molecular alterations.

Cytological findings of NK/T-cell lymphoma in pericardial effusion: A case report with a review of the literature.

Extranodal Natural Killer/T-cell lymphoma (ENKL) is an aggressive NK or cytotoxic T-cell neoplasm. The cytological features of NK/T-cell lymphoma have been rarely described, mainly focusing on the fine needle aspiration cytology from lymph nodes or soft tissue, except for a few cases focused on body fluid. A 46-year-old man visited the hospital due to generalized weakness and weight loss. Three months prior, computed tomographic scan revealed mesenteric panniculitis and reactive lymph nodal enlargement, as well as a mildly thickened left adrenal gland, suggesting an inflammatory condition. About 100 days later, marked enlargement of both adrenal glands with pericardial effusion was noted. The pericardial effusion contained medium-sized atypical lymphocytes, suspicious for malignant lymphoma, and the left adrenal mass was histologically confirmed as ENKL on biopsied specimen. Herein, we describe the cytological features of NK/T-cell lymphoma in body fluid cytology along with a review of the literature.

Cytological evaluation of pericardial fluids: A 5 years experience in tertiary care center.

BACKGROUND: Cytological examination of pericardial effusion fluids is important in diagnosing the etiology of underlying disease, staging, and prognosis of cancer. AIMS AND OBJECTIVES: (1) To study cytological evaluation of pericardial effusions in various pathological conditions in a tertiary care center. (2) To analyze their frequency and clincopathological correlation of the diagnosis. MATERIALS AND METHODS: Our study was a retrospective study performed in the Department of Pathology from 1st January 2012 to 31st December 2016. The study sample included all the pericardial effusions submitted in the pathology department for cytological evaluation. Clinical details and relevant parameters correlated with clinical findings. Each fluid underwent cytospin and cytocentrifuge along with preparation of conventional smears. RESULTS: Of 120 cases, 80% were of benign effusion and 20% were of malignant effusion. Male-to-female ratio was 1.44:1 with patient age ranging from 3 to 90 years. CONCLUSION: Benign effusions can been seen in younger age group and malignant ones in the older age group. The preliminary pericardial fluid analysis in resource-limited settings is the most convenient and cost-effective method for accurate diagnosis. It reduces the demand of invasive investigations and its complications. At times, it is the first test to point toward underlying malignant process thereby affecting the prognosis, survival, and treatment outcome of the patient.

The cell tube block technique and an immunohistochemistry panel including Wilms tumor 1 to assist in diagnosing cavitary effusions in dogs and cats.

BACKGROUND: Cell blocks and immunohistochemistry (IHC) are increasingly recognized as being complementary tools for cytologic diagnostics, especially for neoplastic diseases. OBJECTIVES: The study aimed to evaluate the utility of cell tube block (CTB) IHC for refining the diagnosis of effusions in dogs and cats. METHODS: Cavitary effusions (n = 25) from dogs and cats classified by cytology as reactive, neoplastic, borderline (suspicious of neoplasia), and chylous were studied. CTB sections were stained with H&E, and immunostained with PAX-5, CD3, pancytokeratin (CK), vimentin, and Wilms tumor 1 protein (WT1) antibodies, according to the cytologic diagnoses. A histologic case series of confirmed normal, reactive, and neoplastic mesothelium and several different carcinomas were included to test the utility of WT1 as a marker of mesothelial cells. RESULTS: CTBs had a layered appearance with reduced background staining. CD3 and PAX5 immunolabeling allowed immunophenotype assessment in all of the lymphoma cases. In carcinomatous effusions, neoplastic cells were CK-positive, WT1-negative, and vimentin-negative (except for two cases). Wilms tumor 1 protein was positive in the nuclei of normal, reactive, and neoplastic mesothelial cells, and ovarian carcinomatous cells. Other carcinomas and lymphomas were negative. CONCLUSIONS: CTBs are valuable tools to assist in making a diagnosis of cavitary effusions in dogs and cats, and WT1 is a promising marker to differentiate mesothelial from carcinomatous cells.

Pericardial effusion as first presentation of disseminated non-Hodgkin's lymphoma.

A 46-year-old woman with quiescent lupus presented with worsening pleuritic chest pain and dyspnoea. Bedside echocardiogram confirmed large pericardial effusion with cardiac tamponade. Emergency bedside pericardiocentesis was performed. Pericardial fluid cytology confirmed diffuse large B cell lymphoma, stage four on positron emission tomography. Conventional rituximab, cyclophosphamide, doxorubicin, vincristine and prednisolone chemotherapy achieved good response in all sites except the pericardium. Progressive cardiac involvement was complicated by atrioventricular conduction block requiring permanent pacemaker. Second-line palliative chemotherapy was performed.

Cytopathology of pericardial effusions : Experience from a tertiary center of cardiology.

BACKGROUND: Pericardial effusion (PE) is a common clinical condition that can develop as a result of systemic or cardiac diseases. Here, we report the results of cytology for patients who underwent pericardiocentesis for PE. METHODS: The study comprised 283 patients who underwent primary percutaneous pericardiocentesis between 2007 and 2016. The mean age of the patients was 60.0 ± 16.6 years; 162 (57.2%) were male and 121 (42.8%) were female. The presence of reactive mesothelial cells, acute and chronic inflammatory cells, and/or blood without evidence of malignant cells was considered as benign. The presence of malignant cells with/without reactive mesothelial cells, inflammatory cells, and/or blood was considered as malignant. RESULTS: The vast majority of PE specimens (219 cases; 77.4%) were classified as benign. Only 20 cases (7.1%) were classified as atypical, and malignant cells were present in the PE specimens of 44 cases (15.5%). The most common diagnosis was benign PE. The most commonly encountered malignancy was lung cancer. The rate of malignancy was 1.9% in the serous group and 24% in the hemorrhagic group, which was statistically significant. CONCLUSION: Benign PE was the most frequent cytological diagnosis in our study. Chronic nonspecific pericarditis was the most frequent type of pericarditis in the benign PE group, while lung adenocarcinoma was the most frequent malignancy in the malignant PE group. The rate of malignancy was significantly higher in the hemorrhagic group than in the serous group.

Diagnostic Value of Interferon-γ Release Assays on Pericardial Effusion for Diagnosis of Tuberculous Pericarditis.

Diagnosis of tuberculous pericarditis remains a challenge. We aimed in this study to evaluate the diagnostic value of T-SPOT.TB on pericardial effusion for diagnosis of tuberculous pericarditis. Patients with suspected tuberculous pericarditis were enrolled consecutively between August 2011 and December 2015. T-SPOT.TB was performed on both pericardial effusion mononuclear cells (PEMCs)and peripheral blood mononuclear cells (PBMCs). Sensitivity, specificity, predictive value (PV), and likelihood ratio (LR) of T-SPOT.TB on PEMCs and PBMCs were analyzed. Among the 75 patients enrolled, 24 patients (32%) were diagnosed with tuberculous pericarditis, 38 patients (51%) with nontuberculous pericarditis, and 13 patients (17%) were clinically indeterminate and were excluded from the final analysis. The sensitivity, specificity, positive PV (PPV), negative PV (NPV), positive LR (LR+), and negative LR (LR-) of T-SPOT.TB on PEMCs was 92%,92%,88%,95%,11.61, and 0.09, respectively, compared to 83%, 95%, 91%, 90%,15.83, and 0.18, respectively of T-SPOT.TB on PBMCs. In patients with tuberculous pericarditis, the median frequencies of spot-forming cells (SFCs) of T-SPOT.TB on PEMCs and PBMCs was 172SFCs/106MCs (IQR 39~486), and 66 SFCs/106MCs (IQR 24~526), respectively, but the difference was not statistically significant (P = 0.183). T-SPOT.TB on PEMCs appeared to be a valuable and rapid diagnostic method for diagnosis of tuberculous pericarditis with high sensitivity and specificity.

Converting fluid-based cytologic specimens to histologic specimens for immunohistochemistry.

BACKGROUND: Cavitary effusions are often evaluated cytologically to determine if there is an underlying neoplastic cause. Differentiation of neoplastic epithelial from mesothelial populations within effusions can be difficult using routine cytology. In addition, cytology alone cannot provide information on the immunophenotype of round cell populations. Gel foam techniques can be used to convert effusions into cell blocks for immunohistochemical (IHC) staining which can then be used to differentiate mesothelial from epithelial cell populations, and also allow immunophenotyping of round cell populations within effusions. OBJECTIVES: The aim of this study was to evaluate a gel foam cell block technique for converting potential neoplastic cells in cavitary effusions into cell blocks to characterize these further by IHC. RESULTS: Thirteen canine and 7 feline samples with cohesive cell populations were evaluated using gel foam cell blocks and IHC. Samples evaluated by routine cytology were categorized as (1) epithelial cells, (2) cohesive cell population without cytologic distinction between mesothelial and epithelial cells, and (3) mesothelial cells with signs of atypia. Antibody-mediated staining of vimentin and cytokeratin of the effusion cell blocks yielded further classification of cohesive cell populations. In addition, a total of 4 effusions with malignant round cells were evaluated; they were immunophenotyped as either B- or T-cell lymphoma. CONCLUSION: The use of cytokeratin and vimentin IHC on gel foam cell blocks from cavitary effusions provided robust staining and allowed characterization of cohesive cells as mesothelial or epithelial and immunophenotyping of lymphoid cell populations. In addition, this method is cost and time effective.

Outcomes of an Australian testing programme for epidermal growth factor receptor mutations in non-small cell lung cancer.

BACKGROUND: Molecular characterisation of non-squamous non-small-cell lung cancer (NSCLC) is required to direct optimal treatment. Treatment of NSCLC with inhibitors of epidermal growth factor receptor (EGFR) tyrosine kinase (EGFR-TKI) should be guided by the presence of activating mutations of the EGFR gene. AIM: To gain insight into the rate of testing, the range of tissues samples, test utility and outcome when cost of testing as a barrier to access is removed in the Australian setting. METHODS: In October 2010, a sponsored programme was commenced to gather data on EGFR gene mutation testing in Australia. Partnering laboratories were funded for provision of de-identified results. For participating patients, the programme supported the test charge. Mutation testing was performed using Sanger sequencing of exons 18-21 of the EGFR. RESULTS: Samples 2013 were submitted from 2012 patients. Full sequencing was achieved in 1717 (85%). Failure of full sequencing was more likely in samples derived from fine needle aspiration(FNA) biopsy than tissue biopsy or pleural/pericardial fluid cell blocks OR 3.1 (95% CI 1.9-5.2). There were 359 mutations seen in 337 patients. 14.5% of cases had a classical mutation conferring sensitivity to EGFR-TKI. In addition there was a range of less common mutations - some predicting responses and others of uncertain significance. 1.4% of cases had mutations associated with non-responsiveness to EGFR-TKI. CONCLUSIONS: EGFR gene mutation testing is feasible on local and interstate lung cancer samples. The rate of valid test outcomes is high, but FNA samples are associated with more frequent test failure.

Diagnostic yield of cytologic analysis of pericardial effusion in dogs.

BACKGROUND: Pericardial effusion cytology is believed by many to be of limited value, yet few studies have evaluated its diagnostic utility. OBJECTIVES: To determine the diagnostic utility of cytologic analysis of pericardial effusion in dogs and to determine if consideration of additional data could improve the diagnostic yield. ANIMALS: Two hundred and fifty-nine dogs with cytologic analysis of pericardial effusion performed between April 1990 and June 2012. METHODS: Electronic medical records from a university teaching hospital were retrospectively reviewed; signalment, complete blood count, serum biochemistry, cytologic analysis of pericardial effusion, and echocardiographic data were recorded. Cytology was classified as diagnostic (infectious or neoplastic) or nondiagnostic (hemorrhagic or other) and groups were compared with multiple Student's t-tests. RESULTS: Cytology was grouped as nondiagnostic (92.3%) or diagnostic (7.7%) and characterized as hemorrhagic (90%), neoplastic (4.6%), infectious (3.1%), or other (2.3%). Overall cytologic analysis of pericardial effusion diagnostic utility was 7.7% and increased to 20.3% if the effusion hematocrit (HCT) <10%; echocardiographic evidence of a mass did not result in a significant increase in the diagnostic utility. CONCLUSIONS AND CLINICAL IMPORTANCE: The diagnostic utility of cytologic analysis of canine pericardial effusion is variable depending on the underlying etiology. In this group of dogs, the diagnostic yield of cytologic analysis was greater for pericardial effusion samples in which the HCT was less than 10%.

Immunohistochemical distinction between mesothelial and adenocarcinoma cells in serous effusions: a combination panel-based approach with a brief review of the literature.

BACKGROUND: The prognostic and therapeutic significance of differentiating adenocarcinoma (AC) from reactive mesothelium (RM) in effusions cannot be overemphasized. To avoid diagnostic errors, ancillary techniques like immunohistochemistry are employed. However, results vary and no universal standard has been accepted so far. OBJECTIVE: To study the combined diagnostic efficacy of epithelial membrane antigen (EMA), carcinoembryonic antigen (CEA), E-cadherin (EC), calretinin (CAL), desmin (DES) and vimentin (VIM) in distinguishing RM from AC cells in serous effusions. STUDY DESIGN: Unequivocally diagnosed cases of 39 adenocarcinomatous and 38 RM populations were studied using sections from 49 formalin-fixed, paraffin-embedded cell blocks. MATERIALS AND METHODS: The immunomarkers were applied on cell block sections using the avidin-biotin peroxidase technique. The distribution/intensity of immunostaining in mesothelial and AC cells were graded semiquantitatively. STATISTICAL ANALYSIS USED: Fischer's exact test was used to calculate the efficacy of individual markers and their combinations. RESULTS: EMA was the best single marker for AC, with 100% sensitivity and 97.37% specificity. For the mesothelial cells, CAL exhibited 100% sensitivity and 92.31% specificity. DES was more specific than CAL but had a poor sensitivity of 55.26%. EC, CEA and VIM had unsatisfactory predictive values precluding their use as individual diagnostic markers. Among the combinations, two panels--EMA+ AND (CAL- OR DES-) for ACs and CAL+ AND (EMA- OR CEA-) for RM had 100% specificities and sensitivities. CONCLUSIONS: Most panel studies on fluid cytology are based on the arbitrary use of individual markers with the best statistical values, leading to a less than accurate diagnostic assessment. We believe that statistical parameters calculated in combination provide for a more practical and objective evaluation as well as allowing for meaningful comparative studies.

Analytical validation of the Sysmex XT-2000iV for cell counts in canine and feline effusions and concordance with cytologic diagnosis.

BACKGROUND: The Sysmex XT-2000iV is a hematology analyzer that combines laser and impedance technology. Its usefulness for determining cell counts in canine and feline intracavitary effusions has not yet been studied. OBJECTIVES: The objectives of this study were to evaluate the analytical performance of the Sysmex XT-2000iV for cell counts in effusions from dogs and cats, and to assess correlation with an impedance counter and concordance with diagnoses based on cytologic findings. METHODS: Effusions (43 pleural, 23 peritoneal, 6 pericardial) were analyzed from 32 dogs and 34 cats. Total nucleated cell count (TNCC), HCT, and RBC count were determined on the Sysmex and compared with those obtained on an impedance counter (Hemat 8, SEAC). Imprecision, linearity, and limit of detection were determined for the Sysmex. An algorithm was designed using quantitative and qualitative data from the Sysmex to classify the effusions and the results were compared with diagnoses based on cytologic findings. RESULTS: Intra-assay and interassay coefficients of variation on the Sysmex were variable. Linearity of TNCC was >or=0.993 for dogs and cats, with the exception of effusions from cats with feline infectious peritonitis, which had delta (Delta) TNC values >3.0. In comparison with the Hemat 8, a proportional error was found for TNCC on the Sysmex. Effusion classification based on the algorithm was concordant with that obtained by cytologic examination in 43/72 (60%) samples. Discordant results usually were due to the misclassification of cells with similar morphology (such as mesothelial and carcinoma cells) in Sysmex scattergrams. CONCLUSION: The Sysmex XT-2000iV provides a precise and accurate TNCC and has moderate concordance with cytologic findings for classifying canine and feline effusions. Although microscopic examination of effusions is necessary to achieve an accurate diagnosis, the Sysmex can provide preliminary information that may be helpful to cytopathologists.

Abnormal cytology predicts poor prognosis in cancer patients with pericardial effusion.

PURPOSE: Pericardial tamponade is a life-threatening disorder caused by varying medical conditions. Malignancy and complications of its treatment are a common cause of pericardial effusion. The natural history of pericardial effusion remains largely unknown. We investigated the association of malignancy with adverse outcomes after pericardiocentesis. PATIENTS AND METHODS: Consecutive patients undergoing pericardiocentesis at a single institution between January 1, 1999, and January 31, 2003, were included. Death was confirmed with the Social Security Death Index. Survival estimates were obtained by the Kaplan-Meier method. Cox regression was performed to determine the clinical characteristics associated with death. RESULTS: Two hundred nineteen patients underwent pericardiocentesis during the study period. The effusion was cancer-related in 43.8% of cases. Median survival was 59.6 weeks (95% CI, 24.3 to 94.8 weeks). During the follow-up period, 47.9% of patients died. Cancer-related pericardial effusion was associated with decreased survival (median, 15.1 weeks). Abnormal fluid cytology was further associated with poor prognosis among patients with malignancy (median survival, 7.3 v 29.7 weeks; P = .022). Patients with cancer-related pericardial effusion were more likely to require repeat pericardiocentesis (OR = 6.0; P = .001) and pericardial surgery (odds ratio [OR] OR = 5.7; P < .001). Cancer-related effusion and abnormal cytology were independent predictors of death in a multivariate model. CONCLUSION: Malignancy is the most common cause of pericardial effusion in a tertiary care center. Cancer-related pericardial effusion is associated with adverse outcomes, and abnormal cytology further worsens prognosis. The poor survival among cancer patients with pericardial effusion and abnormal fluid cytology may have important implications for management.

The composition of normal pericardial fluid and its implications for diagnosing pericardial effusions.

BACKGROUND: Pericardial fluid obtained at pericardiocentesis is often subjected to biochemical and hematological analysis, and interpreted using criteria borrowed from pleural effusions. However, the validity and diagnostic yield of this approach is uncertain. Moreover, there is little data regarding the normal composition of the physiological pericardial fluid, which could serve as a reference for pathological effusions. METHODS: Pericardial fluid from 30 patients undergoing elective open heart surgery was collected. Patients were excluded if they had known pericardial disease, had systemic disorders known to be associated with pericardial disease, or if the fluid samples were hemolytic. The biochemical and hematological parameters of the fluid were determined using standard laboratory techniques, and compared with the results obtained for concurrently drawn venous blood. RESULTS: The median age of the study population was 64.5 +/- 10.6 years. Chemistry results of soluble molecules were consistent with the plasma ultrafiltrate nature of the fluid. However, fluid lactate dehydrogenase (LDH) level was unexpectedly high, averaging 2.4 times the serum level, and the mean protein level was 0.6 of the serum level. No correlation was found between comorbidities of patients and fluid characteristics. Fluids contained an average of 1430 leukocytes/muL, with a differential count that was predominated by lymphocytes (53.2 +/- 14%) and monocytes (11.6 +/- 6%). CONCLUSIONS: The composition of the physiologic pericardial fluid is remarkable for high LDH and protein content, and for predominance of lymphocytes. Thus, the biochemical criteria useful for diagnosing pleural effusions are probably not applicable for differentiating transudative from exudative pericardial effusions, and lymphocytosis should be interpreted cautiously.

Flow cytometric analysis of effusions in dogs and cats with the automated haematology analyser ADVIA 120.

Samples were aspirated from 12 thoracic effusions, 10 abdominal effusions and four pericardial effusions in 17 dogs and nine cats. They were analysed cytometrically with the ADVIA 120 flow cytometer and the results were compared with the results of cytological examinations of May-Grünwald-Giemsa-stained smears. The conventional cytology revealed a purulent or pyogranulomatous inflammation in 12 of the animals, lymphoma in six, malignant histiocytosis in two, and an unspecified carcinoma in two; two animals had a chylous effusion, two had a modified transudate, and one dog had an idiopathic pericardial haemorrhage. The flow cytometric analysis was based on cellular volume, peroxidase staining intensity and the determination of nuclear lobularity, and made it possible to identify predominant cell lineages and cell debris, which were shown in characteristic cytograms. Inflammatory effusions, monocytic proliferation and lymphoma were easily detected, but carcinoma cells and mesothelial cells were classified as 'mononuclear blasts'.

The use of CDKN2A deletion as a diagnostic marker for malignant mesothelioma in body cavity effusions.

BACKGROUND: The distinction between benign reactive mesothelial cells and malignant mesothelial cells in serous effusions is difficult and has an unusually high false negative rate. Unfortunately, there are no generally accepted markers to distinguish between benign reactive and malignant mesothelial cells. Homozygous deletion of CDKN2A is frequent in mesothelioma (present in > 70% of tumors). Therefore, detection of CDKN2A deletion by fluorescence in situ hybridization (FISH) was evaluated as an ancillary test in the cytologic diagnosis of malignant mesothelioma. METHODS: Dual-color FISH for CDKN2A and chromosome 9 centromere was performed on cytolyt-fixed Thinprep slides from 6 cytologically suspicious and 7 cytologically positive effusions (all with histologically confirmed mesothelioma) and in 19 cytologically benign effusions (14 pleural effusions, 3 pericardial effusions, and 2 abdominal fluid specimens). Specimens containing > or = 15 nuclei that lacked signals for CDKN2A but showed at least 1 signal for chromosome 9 centromere were considered positive. In samples with negative cytology, the nuclei of at least 100 mesothelial cells were evaluated; whereas, in specimens with positive or suspicious cytology, counting nuclei was done only if < 15% of nuclei showed homozygous loss of CDKN2A. RESULTS: Homozygous deletion was detected in mesothelial cells in six of seven specimens with positive cytology and in six of six specimens with suspicious cytology. Cytologically, there were numerous tumor cells in a single positive specimen without homozygous deletion. All 19 cytologically negative specimens were negative for CDKN2A deletion. CONCLUSIONS: The detection of homozygous CDKN2A deletion by FISH would have been helpful in confirming a diagnosis of mesothelioma over reactive mesothelial cells in 12 of 13 samples with positive or suspicious cytology. Further studies on larger series of patients with suspicious cytology are needed to evaluate the validity and efficiency of this approach for improving the diagnostic accuracy of effusion cytology.

Abdominal, thoracic, and pericardial effusions.

The laboratory evaluation of abdominal, thoracic, and pericardial effusions is a useful diagnostic tool for the assessment of disease states that result in fluid accumulation. Although the numeric values pertaining to cell count and protein content are important, the microscopic evaluation is a critical aspect of the diagnostic procedure; not only does it allow complete classification of the fluid but it allows identification of specific cell types or microorganisms that might be responsible for the fluid accumulation. These findings should always be interpreted in conjunction with the history, signalment, physical findings, and other diagnostic aids in making a definitive diagnosis.