The value of ThinPrep and cytospin preparation in pleural effusion cytological diagnosis of mesothelioma and adenocarcinoma

The diagnosis of malignant mesothelioma requires an integration of the clinical presentation, radiological studies, and immunohistochemical stain of histological sections. Cytological diagnosis on pleural effusions of mesothelioma and pulmonary adenocarcinoma is highly desirable but debatable. A spectrum of cytological features has been found to be associated more commonly with malignant mesothelioma (e.g., peripheral cytoplasmic skirt, bubbly cytoplasm, cyanophilic cytoplasm, and scalloped border of cell balls) vs. adenocarcinoma (e.g., two-cell population, inspissated cytoplasmic material, cytoplasmic vacuole, angulated and indented nuclei, and smooth border of cell balls) to only name a few. The current study is designed to assess whether the introduction of a liquid-based technology such as ThinPrep (TP) can provide additional diagnostic value in addition to the conventional cytospin Diff-Quik (DQ) preparations. Pleural effusion specimens were prepared with split samples for DQ-stained cytospin and Papanicolaou-stained liquid-based TP. Fifteen pleural effusion samples with immunohistologically confirmed malignant mesothelioma and 13 pleural effusion samples of immunohistologically confirmed pulmonary adenocarcinomas were retrieved from our files. Both DQ cytospin- and Papanicolaou-stained TP slides were evaluated for the known cytological features associated with malignant mesothelioma (25 cytological features) and adenocarcinoma (22 cytological features) without knowledge of the original cytological and histological diagnoses. The McNemar test was used to compare these two cytological preparations for both malignant mesothelioma and pulmonary adenocarcinoma. In the malignant mesothelioma group, 4 of 25 cytological features evaluated, bubbly cytoplasm (P = 0.002), vacuolated cytoplasm (P = 0.005), cell-in-cell arrangement (P = 0.007) and irregular nuclear contour (P = 0.083), were seen more frequently in the DQ cytospin preparation, as opposed to only one feature, nuclear size enlargement (P = 0.008), more readily seen using TP. In the pulmonary adenocarcinoma group, only 1 of 22 cytological features evaluated, presence of angulated or indented nuclei (P = 0.025), was seen more frequently in DQ as opposed to two features, presence of two- cell population (P = 0.04) and presence of micropapillary structures (P = 0.1), were seen more readily in TP. All other cytological features evaluated distinguishing mesotheliomas (20 features) and pleural adenocarcinomas (19 features) were seen equally readily in both types of specimen preparation techniques. This study suggests that the liquid-based TP preparation of pleural effusions does not appear to provide additional diagnostic value when compared with the DQ cytospin preparation in the cytological distinction between mesothelioma and adenocarcinoma in pleural effusions. Most cytological features evaluated, 20 of 25 (mesothelioma) and 19 of 22 (adenocarcinoma), can be seen in both preparation techniques.     

Comparison of three cytologic preparation methods and immunocytochemistries to distinguish adenocarcinoma cells from reactive mesothelial cells in serous effusion

We assessed whether a panel of seven antibodies is useful in the differentiation of adenocarcinoma cells (ACCs) from reactive mesothelial cells (RMCs) in effusion samples and to determine optimal specimen preparation conditions for immunocytochemical analysis of effusion samples. Immunocytochemistry (ICC) was performed on three types of effusion preparations from the same effusion specimens: ethanol-fixed smears, ethanol-fixed cell-blocks, and formalin-fixed cell-blocks. Commercially available antibodies MOC-31, Ber-EP4, CA19-9, CEA, EMA, CA125, and HBME-1 were tested on RMCs from four samples of various etiology and 15 samples of adenocarcinoma from various primary sites. Ethanol-fixed smears showed strong immunoreactivity to all antibodies tested. The immunoreactivity of ethanol-fixed and formalin-fixed cell-blocks was significantly lower with all antibodies except CA19-9. Smear preparations are more sensitive than cell-blocks for immunocytochemical study. A panel of antibodies MOC-31, Ber-EP4, CA19-9, and CEA appears to be suitable to distinguish between ACCs and RMCs.     

Utility of immunocytochemistry in diagnosing leptomeningeal metastases from an intrahepatic cholangiocarcinoma

Isolated spinal leptomeningeal metastases (LMM) without brain metastases are infrequent, accounting for about 1% of all solid tumors. In LMM, cerebrospinal fluid (CSF) analyses are mostly abnormal. Demonstrations of intrathecal tumor markers are highly suggestive, but only a positive cytology is diagnostic. The initial CSF cytology can give a false negative result in up to 40–50% of patients with pathologically proven LMM on autopsy. We report a case of intrahepatic cholangiocarcinoma with spinal LMM confirmed using cytokeratin7 and pancytokeratin (AE1/AE3) immunocytochemical studies on paucicellular cerebrospinal fluid cytospin preparation. Given the paucicellularity of the smears and difficult morphologic categorization, immunocytochemistry is vital for confirmatory diagnosis and can help reduce false negative results. To the best of our knowledgethis is the first case report of cytologically confirmed LMM from an intrahepatic cholangiocarcinoma while the patient was undergoing treatment. Diagn. Cytopathol. 2014;42:54–57. © 2013 Wiley Periodicals, Inc.     

Immunocytochemistry of serous effusion specimens: a comparison of ThinPrep vs cell block

The ThinPrep Processor is gaining popularity in both gynecologic and nongynecologic cytologic samples, including effusion specimens. We compared immunocytochemical results on ThinPrep and cell-block preparations from the same effusion specimen with antibodies commonly used in effusion cytopathology. Samples from 17 reactive effusions and 79 effusions with metastatic adenocarcinomas were each prepared as monolayer ThinPreps and formalin-fixed, paraffin-embedded cell blocks. All slides were immunostained with antibodies against intermediate filaments (cytokeratins 8 and 18, and vimentin), cytoplasmic or membrane proteins (EMA, polyclonal CEA, B72.3, and BerEP4), and nuclear antigens (Ki67, PCNA, and p53), using the avidin-biotin procedure. ThinPrep and cell-block slides were stained simultaneously, using identical protocols. Both preparations showed similar results with respect to frequency of positivity, intensity, and distribution of stain for all nonnuclear markers tested. However, for the three nuclear markers Ki67, PCNA, and p53, the frequency and intensity of reaction with ThinPrep were significantly lower than with the cell-block preparation, particularly in malignant effusions. These findings suggest that immunocytochemical results obtained with ThinPrep match those of cell block for most markers tested. However, cell-block preparation are superior to ThinPrep for nuclear markers (Ki67, PCNA, and p53).     

Cytological differential diagnosis among adenocarcinoma,epithelial mesothelioma,and reactive mesothelial cells in serous effusions by immunocytochemistry

The objective of the study is to estimate the expression of some antibodies in the metastatic adenocarcinomas, malignant epithelial mesotheliomas, and reactive mesothelial cells in serous effusions and to choose effective panel to the differential diagnosis. Totally 113 effusion cytology samples (80 pleural fluid, 30 ascitic, and 3 pericardial fluid) from 60 cases of metastatic adenocarcinoma (ACA), 18 cases of malignant epithelial mesothelioma (MM), and 35 cases of reactive mesothelium (RM) were included in this study. The cytological diagnoses of these cases were confirmed by histopathology or clinical datas. Smears and cell blocks were prepared for each case. Immunocytochemical study was performed on the cell block sections. The sensitivity of E‐cadherin, CEA, MOC‐31, and Ber‐EP4 for adenocarcinoma was 86.7%, 80%, 70%, and 76.4%, respectively. The specificity was 98.1%, 96.2%, 92.5%, and 86.8%, respectively. The sensitivity of calretinin, HBME‐1, and thrombomodulin for RM/MM was 83%, 79.2%, and 47.2% respectively. The specificity was 88.3%, 21.7%, and 70%, respectively. The expression of E‐cadherin, CEA, MOC‐31, Ber‐EP4, calretinin, and thrombomodulin showed significant difference between ACA and RM/MM (P < 0.01). The reactivity of EMA and Des showed significant difference between RM and MM (P < 0.01). In our opinion, the antibody panel that consists of E‐cadherin, CEA, calretinin, and thrombomodulin should be the best for differential diagnosis between metastatic adenocarcinomas and RM/MM in serous effusions. EMA and Des should be used to differentiate malignant epithelial mesothelioma and reactive mesothelial cells. EMA positive and Des negative favor MM, while Des positive and EMA negative favor RM. Diagn. Cytopathol. 2011.     

The application of immunocytochemistry to cytologic direct smears of metastatic merkel cell carcinoma

Merkel cell carcinoma represents a highly aggressive cutaneous malignancy characterized by regional recurrences, lymph node metastases, distant metastases, and high mortality. As the cytomorphology of Merkel cell carcinoma can be mimicked by other malignancies, especially lymphoma and pulmonary small cell carcinoma, immunocytochemistry is often useful in confirming the diagnosis. Cell blocks, which are traditionally utilized for immunocytochemistry, occasionally exhibit insufficient cellularity. Hence, we prospectively investigated the application of CK20 immunocytochemistry to air‐dried, unstained direct smears in the diagnosis of Merkel cell carcinoma fine needle aspirates (FNAs). Eight consecutive FNAs of Merkel cell carcinoma were prospectively examined in this series; seven (88%) cases exhibited immunoreactivity for CK20 in the tumor cells. The one CK20‐negative Merkel cell carcinoma was immunoreactive for synaptophysin and CD56. This immunophenotype was identical to that of the original primary tumor. For comparison, air‐dried direct smears prepared from three pulmonary small cell carcinoma FNAs were examined by CK20 immunocytochemistry. In all cases, no CK20 immunoreactivity was seen in any of the tumor cells. In conclusion, direct smears represent a feasible and robust source of cellular material for immunocytochemical studies to diagnose Merkel cell carcinoma. This methodology allows the cytologist to confirm on site that material for diagnostic immunocytochemistry is present thereby serving as a safeguard in instances where insufficient cell block cellularity is anticipated or encountered. Diagn. Cytopathol. 2013;41:729–733. © 2013 Wiley Periodicals, Inc.     

Use of ThinPrep monolayer technique and cytospin preparation in urine cytology: a comparative analysis

We compared the ThinPrep (TP) technique to the cytospin (CS) preparation in the cytological diagnosis of urine by processing 79 specimens by these two techniques. Ten cases were positive for malignancy (six high grade (HG)/carcinoma in situ; four low grade (LG) transitional cell carcinomas (TCC)). Forty-eight cases were within normal limits (59%) and 21 cases had atypical cytological features (19%). The TP technique was better in terms of a cleaner background with fewer obscuring inflammatory cells and blood and with a more even distribution of cells. In general, the cytomorphology was comparable in both techniques. However, in cases with malignancy, CS was relatively superior in the cytomorphologic details; in TP, the diagnostic cells were mostly dispersed as single cells with loss of architectural features and were difficult to find. Artifactual empty spaces and air-drying were more frequently present in TP. In cases contaminated with squamous cells, the urothelial cells were difficult to find in TP. Screening time was comparable for both techniques. In conclusion, to avoid false-negative diagnosis, CS would be complementary to the TP technique in malignant cases and, in particular, those with low cellularity.     

ER,PR, and Her2 immunocytochemistry on cell‐transferred cytologic smears of primary and metastatic breast carcinomas: A Comparison Study With Formalin‐Fixed Cell Blocks and Surgical Biopsies

The use of formalin‐fixed cell blocks (CBs) for detection of ER, PR, and Her2 status of primary and metastatic breast carcinomas sampled by fine‐needle aspiration (FNA) has been extensively used in clinical practice; however, CBs sometimes lack adequate cellularity even when direct smears are cellular. The aim of this study is to assess the reliability of ER, PR, and Her2 status as demonstrated by immunocytochemical staining (ICC) on alcohol‐fixed direct smears using the cell transfer (CT) technique. FNA cases diagnosed as primary or metastatic breast carcinoma in which the status of ER, PR, and Her2 had been determined either on CB or concurrent biopsy were identified over a period of 18 months. ICC for ER, PR, and Her2 was performed on alcohol‐fixed direct smears using the CT technique. Results were compared with those reported for the corresponding formalin‐fixed tissue. A total of 47 FNA specimens from 46 patients were included in this study. ICC results were excluded from analysis if the CT smear contained fewer than 50 cells. Correlation between the ICC performed on the CT smears and the corresponding CB or biopsy revealed a sensitivity rate for ER, PR, and Her2 of 95%, 90%, and 88%, respectively with a specificity of 100% for all three markers. ICC performed on the FNA smears using the CT technique is a reliable method for assessment of the ER, PR, and Her2 status of breast carcinomas, especially when the direct smears are highly cellular and the CB lacks adequate cellularity. Diagn. Cytopathol. 2013. © 2012 Wiley Periodicals, Inc.     

Immunocytochemical panel for distinguishing between adenocarcinomas and reactive mesothelial cells in effusion cell blocks

The aim of our study was to determine the value of a panel that consisted of one epithelial marker (MOC‐31) and two mesothelial markers (D2‐40 and calretinin) for distinguishing between reactive mesothelial cells (RMCs) and adenocarcinomas (ACs) in effusion fluids. A total of 118 cell block specimens from pleural and peritoneal effusions, including 88 ACs and 30 benign effusions with RMCs were stained with antibodies against MOC‐31, D2‐40, and calretinin. MOC‐31 membranous activity was observed in all samples from ACs, regardless of the primary tumor site. All benign effusion samples with RMCs were negative for MOC‐31. All benign effusion samples with RMCs exhibited membranous staining for D2‐40, and one AC case had focal reactivity for D2‐40. Almost all benign effusions reacted positively with calretinin. Staining was noted in both the cytoplasm and the nucleus in the majority of cases. Scattered tumor cells had weak calretinin positivity in two AC cases. Background RMCs in AC effusions were consistently positive for D2‐40 and calretinin. In general, D2‐40 identified more RMCs than calretinin. The staining combination of positive for MOC‐31 and negative for D2‐40 or calretinin were 100% specific and 99% sensitive for ACs. Our data suggest that immunohistochemical studies performed on cell blocks with MOC‐31, D2‐40, and calretinin were useful in the differentiation between ACs and RMCs. D2‐40 was a more sensitive marker for RMCs than calretinin. Diagn. Cytopathol. 2009. © 2009 Wiley‐Liss, Inc.     

Immunohistochemical analysis of gel-transferred cells in cytologic preparations following smear division

Fine-needle aspirations on solid tumors are used increasingly as a means of obtaining a primary diagnosis. In many cases, a panel of immunostains performed on these aspirates is necessary to further characterize the cytologic interpretation. The amount of material obtained through aspiration, however, is often quite limited and is present on few glass slides. Previous studies have demonstrated the success of dividing cytologic smear preparations into smaller parts that could then be used for a panel of immunohistochemical stains. These results, however, did not compare the immunoreactivities of various antibodies before and after tissue transfer on cytologic preparations. In the present study, 41 immunohistochemical stains that employed 16 antibodies on 15 tumor preparations were performed following smear partition using the tissue-transfer technique. The percentage of cells that stained positive after transfer was determined and was correlated quantitatively to the untransferred controls. Specific immunoreactivity was demonstrated in 30 of 38 cases (79%) but was significantly decreased or lost in 8 of 38 cases (21%), which included antibodies for S-100, estrogen and progesterone receptors, chromogranin, neuron-specific enolase, and cytokeratin. Morphology was well preserved following tissue transfer, although limited cytoplasmic damage was seen in up to 25% of tumor cells. Immunopositive samples were found to be easily interpretable. Because sporadic cases fail to show immunohistochemical staining reactions following cytologic smear division and transfer, negative immunohistochemical stains in such preparations should be approached with caution. Diagn. Cytopathol. 1998;18:377–380. © 1998 Wiley-Liss, Inc.     

Osteosarcoma pleural effusion: A diagnostic challenge with some cytologic hints

Pleural effusions can be the first manifestation, recurrence, or metastasis of small round cell sarcomas in children. The most common are Ewing sarcoma, neuroblastoma, and rhabdomyosarcoma. The cytomorphology is variable, the cells can be cohesive, single cells, small or large, morphologically mimicking lymphomas, carcinomas, melanomas, and mesothelioma depending on the sarcoma involved. Osteosarcomas are rare. Their rarity, variable histomorphologic features, immunophenotypic heterogeneity, being of osseous or extraosseous origin and focality of malignant osteoid matrix make their cytologic recognition a diagnostic challenge. They can be confused with small round cell sarcomas, may be misinterpreted as degenerative inflammatory cells, or masked by florid reactive mesothelial hyperplasia particularly in pleural effusions. However, attention to certain cytomorphologic features in smears and cellblock sections should raise suspicion. We report a case of a 9‐year‐old child who presented with cough, chest pain and breathing difficulty, left pleural effusion, a collapsed consolidated lower lung lobe, and a clinical impression of pneumonia. Pleural fluid cytology was initially reported as inflammatory effusion with florid reactive mesothelial hyperplasia. Tissue biopsy of the lung mass showed histomorphologic features consistent with osteosarcoma. A careful look at the cytology materials and cellblock sections showed helpful cytomorphologic features that were masked by florid reactive mesothelial cells and misinterpreted as degenerative inflammatory lymphocytes. An extracellular matrix was a helpful hint. Malignant pleural effusion secondary to osteosarcoma is rare. Cytologic examination may help reach the correct diagnosis if the smears and cellblock sections are carefully evaluated for certain helpful cytomorphologic features, particularly osteoid matrix.     

Comparison of ThinPrep and conventional preparations: Nongynecologic cytology evaluation

ThinPrep processing, an automated cytopreparatory method, has been reported to show good correlation with conventional preparations and to reduce the rate of false-negative diagnoses. In a retrospective review of 230 consecutive nongynecologic cytology cases, we compare the ThinPrep (TP) method with conventional preparations (CP). There were 129 fine-needle aspiration (FNA) specimens from various sites, including 51 breasts, 40 thyroids, 14 lungs, 8 livers, and 16 miscellaneous sites. The sources of 101 body cavity fluids included 68 pleural peritoneal effusions, 25 peritoneal pelvic washings, and 8 miscellaneous sites. Each case was evaluated for cellularity, morphologic details, and obscuring background material. Diagnoses of the TP slides were classified as insufficient, normal, benign, suspicious, or malignant. Each case was then correlated with the tissue diagnosis when available. In TP slides, cellular arrangements, nuclear details, and nuclear cytoplasmic ratio were preserved, while blood and diathesis were eliminated. There was no statistically significant difference between TP and CP in the diagnostic categories. However, in six cases of “insufficient for diagnosis” on FNA by CP. TP yielded sufficient cells and tissue fragments for diagnosis. One case each of FNA and body fluid with a diagnosis of “suspicious for malignancy” by CP was considered “positive” on TP slides. The overall sensitivity of TP was 97.6%, and the specificity was 92.9%. The positive predictive value was 93.0%. We conclude that the ThinPrep method shows good correlation with conventional preparations in both FNA and body fluids. Diagn. Cytopathol. 16:368–371, 1997. © 1997 Wiley-Liss, Inc.     

Diagnostic effects of prolonged storage on fresh effusion samples

The effects on morphology and diagnostic interpretation of delayed processing of refrigerated effusion samples have not been well documented. The potential for cellular degeneration has led many laboratories to reflexively fix samples rather than submit fresh/refrigerated samples for cytologic examination. We sought to determine if effusion specimens are suitable for morphologic, immunocytochemical, and DNA-based molecular studies after prolonged periods of refrigerated storage time. Ten fresh effusion specimens were refrigerated at 4 degrees C; aliquots were processed at specific points in time (days 0, 3, 5, 7, 10, 14). Specimens evaluated included four pleural (3 benign, 1 breast adenocarcinoma) and six peritoneal (2 ovarian adenocarcinomas, 1 malignant melanoma, 2 mesotheliomas, 1 atypical mesothelial) effusions. The morphology of the cytologic preparations from the 10 effusions was preserved and interpretable after 14 days of storage at 4 degrees C. The immunocytochemical profile of the samples (AE1/AE3, EMA, calretinin, and LCA) was consistent from day 0 to day 14. Amplifiable DNA was present in all samples tested on day 14. We conclude that cytopathologic interpretation of effusion samples remains reliable with refrigeration at 4 degrees C even if processing is delayed.     

The application of immunocytochemistry to direct smears in the diagnosis of effusions

Metastatic malignancy represents a common cause of effusions. Immunocytochemistry (ICC) is useful in confirming malignancy and gaining insight into the site of origin. Cell blocks are commonly utilized for this purpose; nonetheless, when the malignant cells are sparse, they may not be represented in cell blocks thereby precluding immunophenotypic characterization. Thus, we sought to investigate the utility of direct smear preparations as a platform for ICC in the diagnosis of effusions. Air‐dried, unstained direct smears were prepared from 49 malignant effusions and 17 reactive effusions for comparison. ICC for EMA and MOC‐31 highlighted the tumor cells in 91 and 98% of the malignant effusions tested, respectively. EMA immunoreactivity was focally observed within the calretinin‐positive mesothelial cell population in 1 (6%) of the 17 reactive effusions. ICC for MOC‐31 was negative in all reactive effusions. Site‐specific immunomarkers were also evaluated. Immunoreactivity for Napsin‐A and TTF‐1 were observed in 78 and 67% of metastatic lung adenocarcinomas, respectively. ICC for PAX8 highlighted metastatic Müllerian and thyroid carcinomas in 100% of cases tested. CDX‐2 immunoreactivity was observed in 25, 60, and 100% of metastatic gastric, pancreatic, and colorectal adenocarcinomas, respectively. Positivity for p63 was observed in 75% of metastatic urothelial cell carcinomas and the one case of pulmonary squamous cell carcinoma examined. Calretinin ICC highlighted the tumor cells in both malignant mesothelioma cases tested as well as the benign mesothelial cells in the reactive effusions. In conclusion, direct smears represent an effective platform for the performance of ICC in the diagnosis of malignant effusions. Diagn. Cytopathol. 2013. © 2012 Wiley Periodicals, Inc.     

Atypical cells in effusions: Diagnostic value of cell image analysis combined with immunocytochemistry

The reliable identification of tumor cells in populations of atypical cells occurring in body cavity effusions is a well-known diagnostic problem. In order to improve tumor cell detection and to predict disease progression, we developed a cell scoring strategy based on a combination of DNA cytophotometry and immunocytochemistry. For this purpose, morphologically atypical cells obtained from 33 effusion samples were submitted to DNA content analysis and tested for Ber-EP4 immunoreactivity. It turned out that elevated DNA content alone has a low specificity (true negative ratio) and sensitivity (true positive ratio) in predicting disease outcome, whereas Ber-EP4 immunoreactivity alone has a high specificity (100%) but a low sensitivity (56%). In contrast, the use of a scoring system combining the two techniques and relating scores to the previous disease state and the cytomorphology of the atypical cells results in highly specific and sensitive prediction of the disease outcome. We therefore suggest that this approach is a valuable tool for reliably identifying tumor cells in effusions containing populations of cytologically suspect cells. Diagn Cytopathol 1996;15: 263–269. © 1996 Wiley-Liss, Inc.     

Diagnostic usefulness of EMA, IMP3, and GLUT-1 for the immunocytochemical distinction of malignant cells from reactive mesothelial cells in effusion cytology using cytospin preparations

To differentiate reactive mesothelial cells (RMs) from metastatic carcinoma and malignant mesothelioma (MM) in effusion cytology is crucial for the cytologic diagnosis and the management of the patients. In the present study, the immunocytochemical staining profile of the epithelial membrane antigen (EMA), the insulin-like growth factor-II mRNA-binding protein 3 (IMP3), and the glucose transporter-1 (GLUT-1) was examined to distinguish RMs from malignant cells. A total of 171 pleural (n = 87) and peritoneal (n = 84) effusion specimens, including 50 benign effusions with RMs, 11 MM effusions, and 110 metastatic malignant effusions, were evaluated for immunocytochemistry. EMA, IMP3, monoclonal GLUT-1, and polyclonal GLUT-1 immunoreactivity were observed in 26.0%, 6.0%, 20.0%, and 18.0% of RMs, respectively. In contrast to RMs, the immunoreactivity in MM was 100%, 36.4%, 100%, and 90.9%; adenocarcinoma (AC) was 100%, 80.8%, 81.7%, and 72.1%; squamous-cell carcinoma was 83.3%, 83.3%, 83.3%, and 66.7%. EMA, IMP3, mGLUT-1, and pGLUT-1 expressions were observed in 98.4%, 65.6%, 88.5%, and 75.4% in the pleural effusion with malignant cells, and 100%, 88.3%, 78.3%, and 71.7% in ascites containing malignant cells, respectively. The findings of the present study indicate that the immunocytochemical staining for EMA, IMP3, and GLUT-1 is a useful diagnostic tool for distinguishing effusions containing malignant cells from those that contain benign cells, and in particular, we suggest that the combination of mGLUT-1 and EMA, and IMP3 and EMA are extremely useful in pleural effusion and in ascites, respectively.     

Pleural metastasis from parotid secretory carcinoma: First report of morphology on effusion cytology,and role of pan-TRK immunohistochemistry

Distant metastasis from salivary gland secretory carcinoma (SC) is rare, with lung and pleura being the most frequent site. While cytological features of SC on fine needle aspirates are well documented, its morphology in serous effusions has not been described. We describe the cytomorphological features on effusion cytology of two patients with ETV6::NTRK3 fusion-positive SC, who subsequently developed pleural metastases. Cytospin preparations of pleural fluid showed tightly cohesive, irregularly shaped and ball-like clusters of large tumor cells with scant to abundant uni- and multi-vacuolated cytoplasm. Nuclei were eccentrically placed, round to oval, vesicular, with finely granular chromatin, irregular nuclear membranes and conspicuous to prominent nucleoli. With these features, the tumors resembled an adenocarcinoma, indistinguishable from a lung primary. Cell blocks from both cases showed tumor fragments, some of which had the hollow appearance of transversely sectioned cell spheres as seen in lung and breast adenocarcinomas. Immunohistochemistry on cell blocks revealed nuclear pan-TRK positivity in both cases. Case 1 also showed focal mammaglobin staining, and TTF1 negativity. Pleural metastases from SC may mimic other adenocarcinomas. As targeted therapy, that is, selective TRK inhibitors are available for treatment of metastatic disease, NTRK3 fusion status is not only diagnostic, but also required to plan treatment. Pan-TRK immunohistochemistry serves as a viable cost-effective, easy to apply surrogate marker for NTRK3 fusion, particularly in diagnostic laboratories lacking easy access to molecular testing on cytological material.