Intrathoracic Lymph Node Microcalcifications are Associated With a High Prevalence of Malignancy and Anaplastic Lymphoma Kinase Rearrangement: The "Calce" Study.

BACKGROUND: Microcalcifications are acknowledged as a malignancy risk factor in multiple cancers. However, the prevalence and association of intrathoracic lymph node (ILN) calcifications with malignancy remain unexplored. METHODS: In this cross-sectional study, we enrolled patients with known/suspected malignancy and an indication for endosonography for diagnosis or ILN staging. We assessed the prevalence and pattern of calcified ILNs and the prevalence of malignancy in ILNs with and without calcifications. In addition, we evaluated the genomic profile and PD-L1 expression in lung cancer patients, stratifying them based on the presence or absence of ILN calcifications. RESULTS: A total of 571 ILNs were sampled in 352 patients. Calcifications were detected in 85 (24.1%) patients and in 94 (16.5%) ILNs, with microcalcifications (78/94, 83%) being the predominant type. Compared with ILNs without calcifications (214/477, 44.9%), the prevalence of malignancy was higher in ILNs with microcalcifications (73/78, 93.6%; P<0.0001) but not in those with macrocalcifications (7/16, 43.7%; P=0.93). In patients with lung cancer, the high prevalence of metastatic involvement in ILNs displaying microcalcifications was independent of lymph node size (< or >1 cm) and the clinical stage (advanced disease; cN2/N3 disease; cN0/N1 disease). The anaplastic lymphoma kinase (ALK) rearrangement was significantly more prevalent in patients with than in those without calcified ILNs (17.4% vs. 1.7%, P<0.001), and all of them exhibited microcalcifications. CONCLUSION: ILN microcalcifications are common in patients undergoing endosonography for suspected malignancy, and they are associated with a high prevalence of metastatic involvement and ALK rearrangement.

World Association for Bronchology and Interventional Pulmonology (WABIP) guidelines on airway stenting for malignant central airway obstruction.

Malignant Central Airway Obstruction (MCAO) encompasses significant and symptomatic narrowing of the central airways that can occur due to primary lung cancer or metastatic disease. Therapeutic bronchoscopy is associated with high technical success and symptomatic relief and includes a wide range of airway interventions including airway stents. Published literature suggests that stenting practices vary significantly across the world primarily due to lack of guidance. This document aims to address this knowledge gap by addressing relevant questions related to airway stenting in MCAO. An international group of 17 experts from 17 institutions across 11 countries with experience in using airway stenting for MCAO was convened as part of this guideline statement through the World Association for Bronchology and Interventional Pulmonology (WABIP). We performed a literature and internet search for reports addressing six clinically relevant questions. This guideline statement, consisting of recommendations addressing these six PICO questions, was formulated by a systematic and rigorous process involving the evaluation of published evidence, augmented with expert experience when necessary. Panel members participated in the development of the final recommendations using the modified Delphi technique.

Diagnostic yield of cone beam CT based navigation bronchoscopy in patients with metastatic lesions: A propensity score matched case-control study.

BACKGROUND: Cone beam CT based Navigation Bronchoscopy (CBCT-NB) has predominantly been investigated as a diagnostic tool in (suspected) primary lung cancers. Small metastatic lesions are clinically considered more challenging to diagnose, but no study has explored the yield of navigation bronchoscopy in patients with pulmonary metastatic lesions (ML) compared to primary lung cancers (PL), correcting for known lesion characteristics affecting diagnostic yield. MATERIALS AND METHODS: This is a single-center, retrospective, propensity score-matched case-control study. We matched a subset of patients who underwent CBCT-NB and received a final diagnosis of pulmonary metastases of solid tumors between December 2017 and 2021 against confirmed primary lung cancer lesions subjected to CBCT-NB in the same time period. The lesions were propensity score matched based on known characteristics affecting yield, including location (upper lobe, lower lobe), size, bronchus sign, and lesion solidity. RESULTS: Fifty-six metastatic pulmonary lesions (mean size 14.7 mm) were individually case-matched to a selection of 297 available primary lung cancer lesions. Case-matching revealed non-significant differences in navigation success rate (PL: 89.3 % vs. ML: 82.1 %, 95%CI on differences: -21.8 to +7.5) and yield (PL: 60.7 % vs. ML: 55.4 %, 95%CI on differences: -25.4 to +14.7). The overall complication rate was comparable (5.4 % in PL vs. 5,4 % in ML). CONCLUSION: After matching primary and metastatic lesions based on CT assessable lesions characteristics, CBCT-NB showed no clinically relevant or significantly different navigation success or yield in either group. We recommend a careful assessment of CT characteristics to determine procedural difficulty rather than selecting based on the suspicion of lesion origin.

Bronchoscopically-visible massive central airway cancer cavitation is associated with metastatic disease, lack of actionable mutations and poor prognosis: a case series.

Cavitating lung tumors occur in approximately 10-15% of the patients, are more commonly associated with squamous histology, and are typically located in the lung parenchyma. Herein we describe an exceedingly rare series of 5 patients, 4 of whom treatment-naïve, whose tumor caused the disruption of the normal airway anatomy at the level of lobar or segmental bronchi, leading to the formation of an endoscopically-visible cavity which ended up in the lung parenchyma or even into the pleural space. Sex (3 males, 2 females), smoking habit (2 never smokers, 2 former smokers, 1 current smoker), and histology (3 adenocarcinoma, 2 squamous cell carcinoma) were heterogeneous, but the 4 patients treatment-naïve presented with metastatic disease, poor ECOG performance status, similar clinical complaints of long duration, and lack of actionable mutations. The only patient who exhibited a meaningful response to treatment had the lowest symptoms' duration, the smallest size of the cavitated mass, and the best performance status at the time of diagnosis. This series provides the first comprehensive description of a rare presentation of lung cancer characterized by similar clinical complaints, delayed diagnosis and poor prognosis.

Leptin-mediated meta-inflammation may provide survival benefit in patients receiving maintenance immunotherapy for extensive-stage small cell lung cancer (ES-SCLC).

BACKGROUND: Only few ES-SCLC patients experience long-term survival benefit by maintenance IT. Adipokines-induced metabolic meta-inflammation has been related to enhanced responsiveness to IT in obese patients; however, their prognostic role in SCLC is currently controversial. METHODS: Pre-treatment CT scan was used for determining distribution of abdominal adiposity, and blood samples were collected at fasting for measuring glycemia, insulin, ghrelin, leptin and adipokines (TNF-α, IFN-γ, IL-6 and MCP-1). Patients with known history of DM type II or metabolic syndrome with HOMA index > 2.5 were considered insulin resistant (IR). RESULTS: In ES-SCLC pts receiving maintenance IT, increased leptin concentration and higher leptin/visceral adipose tissue (VAT) ratio were significantly associated with prolonged PFS. By applying a hierarchical clustering algorithm, we identified a cluster of patients characterized by higher leptin values and lower pro-inflammatory cytokines (TNF-α, IFN-γ and IL-6) who experienced longer PFS (13.2 vs 8.05 months; HR: 0.42 [0.18-0.93] p = 0.02) and OS (18.04 vs 12.09 mo; HR: 0.53 [0.25-1.29] p = 0.07). CONCLUSIONS: Adipokines can play a crucial role to determining effectiveness of anti-cancer immunotherapy. The role of metabolic immune dysfunctions needs further pre-clinical validation and is currently investigated in the larger prospective cohort.

Endobronchial ultrasound in diagnosing and staging of lung cancer by Acquire 22G TBNB versus regular 22G TBNA needles: A randomized clinical trial.

OBJECTIVES: Endobronchial ultrasound guided transbronchial needle aspiration (EBUS-TBNA) has an important role in the diagnosis and staging of lung cancer. Evaluation of programmed death ligand 1 (PD-L1) expression and molecular profiling has become standard of care but cytological samples frequently contain insufficient tumor cells. The 22G Acquire needle with Franseen needle tip was developed to perform transbronchial needle biopsy (TBNB) with improved tissue specimens. This study evaluated if the 22G Acquire TBNB needle results in enhanced PD-L1 suitability rate compared to the regular Expect 22G TBNA needle. METHODS: in this multi-center randomized clinical trial (Netherlands Trial Register NL7701), patients with suspected (N)SCLC and an indication for mediastinal/hilar staging or lung tumor diagnosis were recruited in five university and general hospitals in the Netherlands, Poland, Italy and Czech Republic. Patients were randomized (1:1) between the two needles. Two blinded reference pathologists evaluated the samples. The primary outcome was PD-L1 suitability rate in patients with a final diagnosis of lung cancer. In case no malignancy was diagnosed, the reference standard was surgical verification or 6 month follow-up. RESULTS: 154 patients were randomized (n = 76 Acquire TBNB; n = 78 Expect TBNA) of which 92.9% (n = 143) had a final malignant diagnosis. Suitability for PD-L1 analysis was 80.0% (n = 56/70; 95 %CI 0.68-0.94) with the Acquire needle and 76.7% (n = 56/73; 95 %CI 0.65-0.85) with the Expect needle (p = 0.633). Acquire TBNB needle specimens provided more frequent superior quality (65.3% (95 %CI 0.57-0.73) vs 49.4% (95 %CI 0.41-0.57, p = 0.005) and contained more tissue cores (72.0% (95 %CI 0.60-0.81) vs 41.0% (95 %CI 0.31-0.54, p < 0.01). There were no statistically significant differences in tissue adequacy, suitability for molecular analysis and sensitivity for malignancy and N2/N3 disease. CONCLUSION: The 22G Acquire TBNB needle procured improved quality tissue specimens compared to the Expect TBNA needle but this did not result in an improved the suitability rate for PD-L1 analysis.

Thirty-Day Complications, Unplanned Hospital Encounters, and Mortality after Endosonography and/or Guided Bronchoscopy: A Prospective Study.

BACKGROUND AND OBJECTIVE: Limited data exist regarding the adverse events of advanced diagnostic bronchoscopy, with most of the available information derived from retrospective datasets that primarily focus on early complications. METHODS: We conducted a 15-month prospective cohort study among consecutive patients undergoing endosonography and/or guided bronchoscopy under general anesthesia. We evaluated the 30-day incidence of severe complications, any complication, unplanned hospital encounters, and deaths. Additionally, we analyzed the time of onset (immediate, within 1 h of the procedure; early, 1 h-24 h; late, 24 h-30 days) and identified risk factors associated with these events. RESULTS: Thirty-day data were available for 697 out of 701 (99.4%) enrolled patients, with 85.6% having suspected malignancy and multiple comorbidities (median Charlson Comorbidity Index (IQR): 4 (2-5)). Severe complications occurred in only 17 (2.4%) patients, but among them, 10 (58.8%) had unplanned hospital encounters and 2 (11.7%) died within 30 days. A significant proportion of procedure-related severe complications (8/17, 47.1%); unplanned hospital encounters (8/11, 72.7%); and the two deaths occurred days or weeks after the procedure. Low-dose attenuation in the biopsy site on computed tomography was independently associated with any complication (OR: 1.87; 95% CI 1.13-3.09); unplanned hospital encounters (OR: 2.17; 95% CI 1.10-4.30); and mortality (OR: 4.19; 95% CI 1.74-10.11). CONCLUSIONS: Severe complications arising from endosonography and guided bronchoscopy, although uncommon, have significant clinical consequences. A substantial proportion of adverse events occur days after the procedure, potentially going unnoticed and exerting a negative clinical impact if a proactive surveillance program is not implemented.

Possible Use of Linear Echobronchoscope for Diagnosis of Peripheral Pulmonary Nodules.

Echobronchoscope-guided transbronchial needle aspiration (EBUS-TBNA) is mainly used as the transbronchial approach to hilar/mediastinal lymph nodes or lesions, for diagnostic or staging purposes. Moreover, the role of linear EBUS-TBNA as a diagnostic tool for central intrapulmonary lesions adjacent to the trachea or the major bronchi is also well established. However, since the tip of the ultrasound probe at the distal end of the echobronchoscope is very thin, it can be wedged through smaller peripheral bronchi, reaching the distal parenchyma and allowing for peripheral pulmonary lesion sampling. The main aim of this retrospective study was to evaluate the diagnostic yield and the safety of EBUS-TBNA in the diagnosis of pulmonary peripheral nodules. The database of the Interventional Pulmonology Unit of Azienda Ospedaliero-Universitaria delle Marche (Ancona, Italy) was evaluated to identify peripheral pulmonary nodules approached by EBUS-TBNA. Thirty patients with a single peripheral pulmonary nodule located peripherally to the subsegmental bronchi of the lower lobes and adjacent to a small bronchus greater than 3 mm in diameter were included in this study. The nodule was visible using endoscopic ultrasound in 28 patients and the diagnosis was obtained via EBUS-TBNA in 26 cases (12 adenocarcinoma, 5 typical carcinoid tumors, 4 hamartoma and 5 metastatic lesions). The diagnostic yield was 86.6% for all 30 patients and 92.8% if only the 28 patients in which the lesion was visualized via echobronchoscopy were considered. No relevant adverse events were observed. We conclude that EBUS-TBNA may be an effective and safe option to sample pulmonary peripheral nodules in selected patients with lower lobe peripheral pulmonary lesions adjacent to small bronchi greater than 3 mm in diameter and reachable with the EBUS-TBNA probe.

Lung cancer multi-omics digital human avatars for integrating precision medicine into clinical practice: the LANTERN study.

BACKGROUND: The current management of lung cancer patients has reached a high level of complexity. Indeed, besides the traditional clinical variables (e.g., age, sex, TNM stage), new omics data have recently been introduced in clinical practice, thereby making more complex the decision-making process. With the advent of Artificial intelligence (AI) techniques, various omics datasets may be used to create more accurate predictive models paving the way for a better care in lung cancer patients. METHODS: The LANTERN study is a multi-center observational clinical trial involving a multidisciplinary consortium of five institutions from different European countries. The aim of this trial is to develop accurate several predictive models for lung cancer patients, through the creation of Digital Human Avatars (DHA), defined as digital representations of patients using various omics-based variables and integrating well-established clinical factors with genomic data, quantitative imaging data etc. A total of 600 lung cancer patients will be prospectively enrolled by the recruiting centers and multi-omics data will be collected. Data will then be modelled and parameterized in an experimental context of cutting-edge big data analysis. All data variables will be recorded according to a shared common ontology based on variable-specific domains in order to enhance their direct actionability. An exploratory analysis will then initiate the biomarker identification process. The second phase of the project will focus on creating multiple multivariate models trained though advanced machine learning (ML) and AI techniques for the specific areas of interest. Finally, the developed models will be validated in order to test their robustness, transferability and generalizability, leading to the development of the DHA. All the potential clinical and scientific stakeholders will be involved in the DHA development process. The main goals aim of LANTERN project are: i) To develop predictive models for lung cancer diagnosis and histological characterization; (ii) to set up personalized predictive models for individual-specific treatments; iii) to enable feedback data loops for preventive healthcare strategies and quality of life management. DISCUSSION: The LANTERN project will develop a predictive platform based on integration of multi-omics data. This will enhance the generation of important and valuable information assets, in order to identify new biomarkers that can be used for early detection, improved tumor diagnosis and personalization of treatment protocols. ETHICS COMMITTEE APPROVAL NUMBER: 5420 - 0002485/23 from Fondazione Policlinico Universitario Agostino Gemelli IRCCS - Università Cattolica del Sacro Cuore Ethics Committee. TRIAL REGISTRATION: clinicaltrial.gov - NCT05802771.

High-Definition Videobronchoscopy for the Diagnosis of Airway Involvement in Sarcoidosis: The Enhance Sarcoidosis Multicenter Study.

BACKGROUND: The ability of high-definition (HD) videobronchoscopy to detect airway involvement in sarcoidosis has not been evaluated previously. RESEARCH QUESTION: What is the role of HD videobronchoscopy in the identification of sarcoidosis-associated airway abnormalities (AAs)? What are the patterns of AAs more commonly observed and more frequently associated with the detection of granulomas in endobronchial biopsy (EBB)? STUDY DESIGN AND METHODS: In this prospective international multicenter cohort study, consecutive patients with suspected sarcoidosis underwent airway inspection with an HD videobronchoscope and EBB using a standardized workflow. AAs were classified according to six patterns defined a priori: nodularity, cobblestoning, thickening, plaque, increased vascularity, and miscellaneous. We assessed diagnostic yield of EBB, prevalence of AAs, and interobserver agreement for different patterns of AAs. RESULTS: AAs were identified in 64 of 134 patients with sarcoidosis (47.8%), with nodularity (n = 23 [17.2%]), plaque (n = 19 [14.2%]), and increased vascularity (n = 19 [14.2%]) being the most prevalent. The diagnostic yield of EBB was 36.6%. AAs were significantly more prevalent in patients with than in those without nonnecrotizing granulomas on EBB (67.4% vs 36.5%; P = .001). Likewise, parenchymal disease on CT scan imaging was significantly more common in patients with than in those without nonnecrotizing granulomas on EBB (79.6% vs 54.1%; P = .003). On a per-lesion analysis, nonnecrotizing granulomas were seen especially in EBB samples obtained from areas of cobblestoning (9/10 [90%]) and nodularity (17/29 [58.6%]). The overall diagnostic yield of random EBB was low (31/134 [23.1%]). The interobserver agreement for the different patterns of AA was fair (Fleiss κ = 0.34). INTERPRETATION: In a population with a large prevalence of White Europeans, HD videobronchoscopy detected AAs in approximately one-half of patients with sarcoidosis. The diagnostic yield of EBB was higher in patients with parenchymal involvement on CT scan imaging and in those with AAs, especially if manifesting as cobblestoning and nodularity. TRIAL REGISTRY: ClinicalTrials.gov; No.: NCT4743596; URL: www. CLINICALTRIALS: gov.

Rate and Predictors of Unforeseen PN1/PN2-Disease in Surgically Treated cN0 NSCLC-Patients with Primary Tumor > 3 cm: Nationwide Results from Italian VATS-Group Database.

Background. Since no robust data are available on the real rate of unforeseen N1-N2 disease (uN) and the relative predictive factors in clinical-N0 NSCLC with peripheral tumours > 3 cm, the usefulness of performing a (mini)invasive mediastinal staging in this setting is debated. Herein, we investigated these issues in a nationwide database. Methods. From 01/2014 to 06/2020, 15,784 thoracoscopic major lung resections were prospectively recorded in the "Italian VATS-Group" database. Among them, 1982 clinical-N0 peripheral solid-type NSCLC > 3 cm were identified, and information was retrospectively reviewed. A mean comparison of more than two groups was made by ANOVA (Bonferroni correction for multiple comparisons), while associations between the categorical variables were estimated with a Chi-square test. The multivariate logistic regression model and Kaplan-Meyer method were used to identify the independent predictors of nodal upstaging and survival results, respectively. Results. At pathological staging, 229 patients had N1-involvement (11.6%), and 169 had uN2 disease (8.5%). Independent predictors of uN1 were SUVmax (OR: 1.98; CI 95: 1.44-2.73, p = 0.0001) and tumour-size (OR: 1.52; CI: 1.11-2.10, p = 0.01), while independent predictors of uN2 were age (OR: 0.98; CI 95: 0.96-0.99, p = 0.039), histology (OR: 0.48; CI 95: 0.30-0.78, p = 0.003), SUVmax (OR: 2.07; CI 95: 1.15-3.72, p = 0.015), and the number of resected lymph nodes (OR: 1.03; CI 95: 1.01-1.05, p = 0.002). Conclusions. The unforeseen N1-N2 disease in cN0/NSCLCs > 3 cm undergoing VATS resection is observable in between 12 and 8% of all cases. We have identified predictors that could guide physicians in selecting the best candidate for (mini)invasive mediastinal staging.

Ultrasound-Guided Needle Aspiration Biopsy of Superficial Metastasis of Lung Cancer with and without Rapid On-Site Evaluation: A Randomized Trial.

BACKGROUND AND OBJECTIVE: Studies which evaluated the role of an ultrasound-guided needle aspiration biopsy (US-NAB) of metastases from lung cancer located in "superficial" organs/tissues are scant, and none of them assessed the possible impact of rapid on-site evaluation (ROSE) on diagnostic accuracy and safety outcomes. METHODS: Consecutive patients with suspected superficial metastases from lung cancer were randomized 1:1 to US-NAB without (US-NAB group) or with ROSE (ROSE group). The diagnostic yield for a tissue diagnosis was the primary outcome. Secondary outcomes included the diagnostic yield for cancer genotyping, the diagnostic yield for PD-L1 testing, and safety. RESULTS: During the study period, 136 patients were randomized to receive an US-NAB with (n = 68) or without ROSE (n = 68). We found no significant differences between the ROSE group and the US-NAB group in terms of the diagnostic yields for tissue diagnosis (94.1% vs. 97%, respectively; p = 0.68), cancer genotyping (88% vs. 91.8%, respectively; p = 0.56), and PD-L1 testing (93.5% vs. 90.6%, respectively; p = 0.60). Compared to the diagnostic US-NAB procedures, the non-diagnostic procedures were characterized by less common use of a cutting needle (66.6% vs. 96.9%, respectively; p = 0.0004) and less common retrieval of a tissue core (37.5% vs. 98.5%; p = 0.0001). Only one adverse event (vasovagal syncope) was recorded. CONCLUSION: US-NAB of superficial metastases is safe and has an excellent diagnostic success regardless of the availability of ROSE. These findings provide a strong rationale for using US-NAB as the first-step method for tissue acquisition whenever a suspected superficial metastatic lesion is identified in patients with suspected lung cancer.

Accuracy and Predictors of Success of EUS-B-FNA in the Diagnosis of Pulmonary Malignant Lesions: A Prospective Multicenter Italian Study.

BACKGROUND: The role of endoscopic ultrasound with bronchoscope fine-needle aspiration (EUS-B-FNA) in the diagnosis of suspected malignant pulmonary lesions adjacent to the esophagus has been poorly investigated. The aim of the present study was to assess the accuracy of EUS-B-FNA for the diagnosis and molecular profiling of paraesophageal pulmonary lesions, as well as its predictors of success. MATERIALS AND METHODS: Patients who underwent EUS-B-FNA for the diagnosis of paraesophageal lesions were consecutively enrolled in four Italian centers. Demographic, clinical, procedural, pathological, and molecular characteristics of the malignant samples were collected. The primary outcome was the diagnostic accuracy for pulmonary malignancies. Secondary outcomes were diagnostic yield and predictors of success for diagnosis and molecular profiling. RESULTS: 107 adult patients (60 [56.1%] males; median (interquartile range) age: 69 [60-70] years) were enrolled. The diagnostic accuracy of EUS-B-FNA was 95.3% in the overall cohort and 95.2% in the 99 patients with a final diagnosis of malignancy. Neither clinical nor procedural variables significantly affected the diagnostic accuracy, whereas rapid on-site evaluation (ROSE), performed by pathologists or trained pulmonologists, was a strong predictor for a complete molecular profiling (OR [95% CI]: 12.9 [1.2-137.4]; p value: 0.03). CONCLUSION: EUS-B-FNA is a safe and accurate method for the diagnosis of paraesophageal pulmonary lesions. The presence of ROSE is relevant for a complete molecular profiling in this selected cohort of patients with advanced lung cancer.

Interobserver agreement of PD-L1 (SP263) assessment in advanced NSCLC on cytological smears and histological samples.

BACKGROUND: The PD-L1 assessment is mandatory for the selection of patients affected by advanced non-small-cell lung cancer (NSCLC) who can benefit from the PD-1/PD-L1 checkpoint inhibitors therapy. Previous studies tested PD-L1 on cytological smears to evaluate this sample as an alternative to formalin-fixed paraffin-embedded (FFPE) ones, but several critical issues needed to be clarified. AIM: We evaluated the cyto-histological agreement (CHA) and the PD-L1 interobserver agreement (IrOA) among three different pathologists (Path1, Path2, Path3) on 160 paired cytological smears and histological samples of advanced NSCLC. RESULTS: With the cut-off of < 50%/≥ 50%, CHA resulted good for Path1 (Cohen's k: 0.702) and Path3 (Cohen's k: 0.731), moderate for Path2 (Cohen's k: 0.576) adopting the same cut-off, the IrOA was moderate (ICC 0.72 [95% CI: 0.63-0.78]) for smears and good for histological samples (ICC 0.85 [95% CI: 0.80-0.85]). CONCLUSION: With a cut-off system of < 50%/≥ 50%, PD-L1 assessment shows moderate to good CHA and exhibited moderate IrOA on smears and good IrOA on FFPE. As result, PD-L1 assessment should be improved on cytological smears as well as could be a suitable alternative for patients without FFPE samples and not eligible for pembrolizumab, adopting a cut-off of < 50%/≥ 50%; presumably, an appropriate pathologist training could further improve the reproducibility.

The value of cytology in distinguishing malignant mesothelioma: An institutional experience of 210 cases reclassified according to the International System for Reporting Serous Fluid Cytopathology (ISRSFC).

OBJECTIVE: Malignant mesothelioma (MM) is usually diagnosed by histological examination of tissue samples; however, effusion cytology offers an opportunity to identify a strong possibility for mesothelioma diagnosis at an early stage. We conducted a retrospective analysis of cytological specimens from a large series of histologically proven MM diagnosed over 19 years. The cases were reviewed and reclassified according to the International System for Reporting Serous Fluid Cytopathology (ISRSFC). METHODS: A total of 450 cases were identified. Cytological analysis was present in 210 patients (164 pleural and 46 peritoneal effusions). All cases were reviewed and reclassified according to the proposed ISRSFC scheme. A comparison among the cytomorphological features was made throughout the different diagnostic categories. RESULTS: The 210 cases were histologically diagnosed as follows: 192 (91.4%) cases had an epithelioid type and 18 (8.6%) had a sarcomatoid subtype of MM. The cytological cases were reclassified as follows: 2 (0.9%) as non-diagnostic (ND), 81 (38.6%) as negative for malignancy (NFM), 4 (1.9%) as atypia of undetermined significance (AUS), 11 (5.2%) as suspicious for malignancy (SFM), 112 (53.4%) as malignant (MAL). Sarcomatoid cells in the MAL category were characterised cytomorphologically by more pronounced discohesion. In comparison with the epithelioid subtype, the tumour cells appeared solitary with moderate or marked nuclear pleomorphism, and irregular chromatin. CONCLUSIONS: It is important to recognise the cytological characteristics of this aggressive entity to suggest an early and precise possible diagnosis. Morphological features, coupled with clinico-radiological data may help the clinicians in adequately managing the patients.