Flow cytometry in diagnostic cytology

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.

Artificial Neural Networks as Decision Support Tools in Cytopathology: Past, Present, and Future

OBJECTIVE

This study aims to analyze the role of artificial neural networks (ANNs) in cytopathology. More specifically, it aims to highlight the importance of employing ANNs in existing and future applications and in identifying unexplored or poorly explored research topics.

STUDY DESIGN

A systematic search was conducted in scientific databases for articles related to cytopathology and ANNs with respect to anatomical places of the human body where cytopathology is performed. For each anatomic system/organ, the major outcomes described in the scientific literature are presented and the most important aspects are highlighted.

RESULTS

The vast majority of ANN applications are related to cervical cytopathology, specifically for the ANN-based, semiautomated commercial diagnostic system PAPNET. For cervical cytopathology, there is a plethora of studies relevant to the diagnostic accuracy; in addition, there are also efforts evaluating cost-effectiveness and applications on primary, secondary, or hybrid screening. For the rest of the anatomical sites, such as the gastrointestinal system, thyroid gland, urinary tract, and breast, there are significantly less efforts relevant to the application of ANNs. Additionally, there are still anatomical systems for which ANNs have never been applied on their cytological material.

CONCLUSIONS

Cytopathology is an ideal discipline to apply ANNs. In general, diagnosis is performed by experts via the light microscope. However, this approach introduces subjectivity, because this is not a universal and objective measurement process. This has resulted in the existence of a gray zone between normal and pathological cases. From the analysis of related articles, it is obvious that there is a need to perform more thorough analyses, using extensive number of cases and particularly for the nonexplored organs. Efforts to apply such systems within the laboratory test environment are required for their future uptake.

Flow immunocytochemistry of marker expression in cells from body cavity fluids

Diagnostic cytology based on the examination of cells from body cavity fluids misses approximately 50% of patients with a proven malignancy. In an earlier study, we used immunohistochemical detection of epithelial membrane antigen expression with flow cytometric detection of DNA aneuploidy to reduce the number of false negatives. In the present study, we have combined DNA flow cytometry with flow cytometric detection of marker expression to analyze cells from body cavity fluids. Seventy-nine specimens of ascites and pleural fluids were analyzed by diagnostic cytology, DNA flow cytometry, and for the expression of the following markers: Ber-EP4, progesterone (PR), MUC4, and thyroid transcription factor-1 (TTF-1). DNA index of equal to or greater than 1.2 was seen in 33/79 (41.7%) of the samples. Statistical analysis of 79 samples in which data from cytology, DNA aneuploidy, and expression of at least one of the markers was available showed that by combining data from positive marker expression with that of aneuploidy, the sensitivity was increased from 58.5 to 100%. In contrast, out of the 38 samples designated as non-malignant by diagnostic cytology, nine had aneuploid DNA content and 16 of the diploid samples had a positive marker expression. Specificity was reduced from 74.7 to 31.6% due to the presence of aneuploidy and marker expression in these samples. ALDH1(pos)/CD44(pos)/CD24(neg) expression has been reported to be associated with human breast tumor stem cells. Some of our samples had cells with this phenotype. Flow cytometry offers the advantage of rapid multiparametric analysis of DNA aneuploidy and marker expression in cells from body cavity fluids based on the analysis of a large number of cells without observer bias. By further developing the use of specific markers and aneuploidy, it may be possible to refine flow cytometric analysis for rapid detection of malignant cells in body cavity fluids.

Scanning flow cytometer modified to distinguish phytoplankton cells from their effective size, effective refractive index, depolarization, and fluorescence

A laser flow cytometer based on scanning flow cytometry has been assembled. The unpolarized and linearly polarized light-scattering profiles, as well as the side emitted light in different spectral bands, were measured, allowing the simultaneous and real-time determination of the effective size and the effective refractive index of each spherelike particle. Additionally, each particle could be identified from depolarization and fluorescence measured simultaneously. The tests with aqueous samples of polystyrene spheres, fluorescent or nonfluorescent, and phytoplankton cells demonstrate that the system is able to retrieve size and refractive index with an accuracy of 1% and that the depolarization and fluorescence measurements allow the classification of particles otherwise indistinguishable.

Flow cytometric analysis of effusions in dogs and cats with the automated haematologyanalyser 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'.

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.

DNA cytometric features in biopsies of TaT1 urothelial cell cancer predict recurrence and stage progression more accurately than stage, grade, or treatment modality

OBJECTIVES

To compare retrospectively the predictive value for recurrence and stage progression of DNA ploidy and S-phase fraction by flow cytometry and highly automated ultrafast image cytometry (ICM) in biopsies of TaT1 urothelial cell carcinomas (UCCs) of the urinary bladder with stage, grade, other pathologic features, and treatment.

METHODS

Three experienced pathologists reviewed the stage and grade of 228 UCCs; 193 (85%) consensus cases were analyzed further. We had enough material for single-cell suspensions for both flow cytometry and ICM in 183 cases (94.8%). The 2001 European Society for Analytical Cellular Pathology standards for DNA ICM were followed. The predictive value of DNA features, classic prognosticators (stage, grade, carcinoma in situ, multicentricity), and treatment modality for recurrence and stage progression were analyzed with univariate (Kaplan-Meier) survival and multivariate (Cox model) regression analysis. Ta and T1 cases were analyzed separately.

RESULTS

Of the 228 cases, 88 (51.5%) recurred and 13 (7.6%) progressed. On univariate analysis, most of the DNA features studied were statistically significant. Treatment modality and grade were only prognostic for progression (not for recurrence) and only in Ta cases. On multivariate analysis, DNA ICM features performed best; the strongest recurrence predictor for Ta UCC was a DNA index (DI) of 1.0 versus all others, and for T1 UCC, a DI of less than 1.3 versus 1.3 or greater. The best stage progression predictor for Ta UCCs was a DI of 1.0 plus an S-phase fraction of less than 10%, and for T1 UCCs, a DI of less than 1.3 versus 1.3 or greater. With multivariate analysis, sex, age, grade, carcinoma in situ, multicentricity, and treatment modality were excluded once the DNA ICM features were selected.

CONCLUSIONS

DNA image cytometric features predict recurrence and stage progression in TaT1 UCC biopsies more accurately than classic prognostic factors, independent of treatment modality.

Lymphoid and myeloid neoplasms involving cerebrospinal fluid: comparison of morphologic examination and immunophenotyping by flow cytometry

We studied 53 samples of cerebrospinal fluid (CSF) by cytologic examination and immunophenotyping by flow cytometry. The samples were taken from 43 patients; 25 had a previous diagnosis of malignant lymphoma/leukemia and the remaining 18 a variety of other diseases involving the central nervous system (CNS). Lymphoma/leukemia was detected in 21 samples: 12 by morphologic examination and immunophenotyping and nine by immunophenotyping alone. There were two cases with a suspicious morphologic examination and negative immunophenotyping in which the final diagnosis were cryptococcal and viral meningitis. In the group of 18 patients, one was diagnosed as a primary malignant lymphoma of the CNS and was positive with cytology and immunophenotyping. The other 17 were negative with both methods and follow-up showed no evidence of lymphoma/leukemia. This study shows that morphologic examination combined with flow cytometry enhances the detection rate by 75% over morphologic examination alone in CSF samples.

Neoplastic masquerade syndromes

Masquerade syndromes are classically defined as entities which emulate inflammatory conditions but which are in fact due to a neoplastic process. Careful history and examination in concert with appropriate ancillary investigations and histopathologic evaluation of tissue specimens are required in order to make the correct diagnosis. Many conditions may result in an appearance mimicking an inflammatory condition. The authors review neoplastic conditions which may be considered masquerades. The most common of these is primary intraocular lymphoma or primary central nervous system lymphoma, occurring predominately in older individuals. Diagnostic strategies, therapy, and prognosis are reviewed in detail. Other conditions that can be considered masquerade syndromes are reviewed as well, including lymphomatous and nonlymphomatous conditions, such as melanoma, retinoblastoma, juvenile xanthogranuloma, metastatic lesions, and paraneoplastic syndromes, among others.

[Flow cytometric DNA analysis and cytology in diagnosis and prognosis of bladder tumors: preliminary results of a comparative study of bladder lavage]

OBJECTIVE

To compare flow cytometric data (ploidy and proliferative activity or percentage SG2M-phase cells) to cytologic and histologic data of the bladder carcinomas.

MATERIALS AND METHODS

Cytologic and flow cytometric analysis of DNA content were performed on 48 bladder washings: 28 bladder washings from patients being followed for urothelial carcinomas and 20 control washings from individuals undergoing cytoscopy for other reasons.

RESULTS

Cytological sensitivity and specificity of bladder washing were 75% and 91% respectively. Specificity was increased to 94% using flow cytometric DNA analysis whereas sensibility was moderately decreased to 68%. Combination of flow cytometry and cytology increased the diagnostic yield to 100%. The study of the patient group showed an increased abnormalities (aneuploidy and/or proliferate activity SG2M > 10%) according to the tumor grading and tumor staging. A cytometric test was positive in 80% for G3 tumours and in 68% for G2 tumours. The staging tumor was positive in 46%, 89% and 100% of the pTa-pT1, pT2 and pT4 tumours respectively. Otherwise the comparison of control group with patients showed a statistical correlation between cytometric test, staging tumour and tumoral grading as showed in the following groups: control/G1-G2 (p < 0.05), control/G3 (p < 0.001), control/pTa-pT (p < 0.05), control/pT2-pT4 (p < 0.001).

CONCLUSION

We confirmed through this study the interest of the flow cytometric DNA analysis in the diagnosis and prognosis of bladder carcinomas, and we showed the importance of the histogram classification in order to facilitate their interpretation and to avoid the trap of false aneuploidy.

Pitfalls in TRAP assay in routine detection of malignancy in effusions

Telomerase has been found to be reactivated in a majority of cancers but is inactive in most somatic cells. Our principal goal was to determine the potential use of the telomeric repeat amplification protocol (TRAP) assay as marker for malignancy in cytological effusions. The simple selection criterion was the cytological diagnosis, and routine samples were classified into malignant (58 samples) and nonmalignant (233 samples). Of the malignant samples, 44/58 (76%) were positive by TRAP assay. Of the 14 telomerase-negative cytology-positive samples, RNA integrity was poor in 9, indicating suboptimal sample conservation for molecular analysis. In 3 of the remaining 5 samples with a negative TRAP assay, a high number of malignant cells was observed, and these cells might have been telomerase-negative. Thus, the sensitivity of TRAP assay for the presence of malignant cells was about 76%. In the cytologically nonmalignant effusions, the presence of telomerase activity was observed in 24% (55/233). Of these, 6% were highly suspicious for malignancy, 9% were doubtful, and 9% were cytologically nonmalignant effusions confirmed by a follow-up of 12 mo or more. According to these data, the specificity of the TRAP assay to detect tumor cells in effusions ranged only between 82-91%. Our results indicate that, although the TRAP assay is positive in 6-15% of putative malignant effusions, the relatively high number of TRAP false-negative and false-positive cases renders this test unsuitable for routine diagnostic purposes.

Detection of malignant effusions: comparison of a telomerase assay and cytologic examination

Telomerase is inactive in most somatic cells, but has been found to be reactivated in a majority of cancers. Our principal goal was to test whether the presence of telomerase activity concurred with positive cytology, and was thus of potential use in detecting cancer cells in effusions. The telomeric repeat amplification protocol (TRAP) assay and cytological examination were performed in a blinded fashion on 91 unselected effusions, for which laboratory processing was done according to standard procedures. In our series, 30% (27/91) of samples were found to be malignant by cytology. Of these, 19 (70%) were also positive in the TRAP assay. Of the 8 telomerase-negative cytology-positive samples, RNA integrity was generally poor, indicating suboptimal sample conservation for molecular analysis. Negative cytology in the presence of telomerase activity was observed in 17 effusions. Of these, 11 were from patients with advanced cancer, and thus a diagnosis of malignant effusion should be suspected. The TRAP assay for telomerase activity holds promise in the analysis of effusions, but its routine use as an adjunct to cytology awaits further confirmation of its positive predictive value.

Analysis of cerebrospinal fluid cells by flow cytometry and immunocytochemistry in inflammatory central nervous system diseases: comparison of low- and high-density cell surface antigen expression

The examination of cerebrospinal fluid (CSF) continues to play an important role in the diagnosis of inflammatory diseases of the central nervous system (CNS). Immunocytochemistry and flow cytometry are the most commonly used methods for analysis of surface markers on CSF cells. We here compared these methods in the examination of CSF cells from a total of 68 patients with acute and chronic inflammatory CNS diseases. Expression of costimulatory molecules CD80 (B7-1) and CD86 (B7-2) as activation markers that are present at low density on the cell surface was analyzed in comparison to CD22 (B-cells) and CD4 (T-cell subset), that show high staining intensities. For CD22 and CD4, the results obtained with both methods were similar and reliable. Using flow cytometry, CD80 expression was detected in 6% of CSF cells in patients with chronic inflammatory CNS disease, as compared to 2% using immunocytochemistry, where the reliability of the data was found to be higher. We conclude that for examination of low-density surface markers on CSF cells, particularly with low cell counts, immunocytochemistry may be more reliable.

Benign and malignant cells in effusions: diagnostic value of image DNA cytometry in comparison to cytological analysis

Identifying tumor cells in body cavity fluids reliably is a well-known diagnostic problem. Since cytometric quantitation of nuclear DNA content appears to be a promising new tool in the diagnosis and prognostic evaluation of many solid human tumors, we examined its validity in detecting malignant cells in cytologically positive effusions. For this purpose, image DNA cytometric measurements, including the evaluation of DNA-ploidy and the calculation of the DNA index (DI), were performed in 80 body cavity fluids. The results were correlated with cytology, clinical course and final histological diagnoses. We used aneuploidy, as shown by interactive image DNA cytometry, as a marker for the malignancy of cells that occur in body cavity fluids with a 100% specificity and 94.8% sensitivity. Cytological investigation showed a 92.3% specificity and 95.4% sensitivity. Combining both methods raised the specificity to 100% and the sensitivity to 98.5% and had a positive predictive value of 100% and a negative predictive value of 93.8%. The DNA-index (DI) was significantly higher in malignant effusions than in benign effusions: 1.5 +/- 0.74 (mean +/- SD) versus 1.11 +/- 0.26 (p < 0.05). Along with the difficult cytological evaluation of malignant cells in body cavity fluids, image DNA cytometry can be a helpful additional method for evaluating these cells. Combining the two techniques results in a highly specific and sensitive prediction of malignant cells. We, therefore, suggest using these methods for the reliable identification of tumor cells in effusions.