Efficacy and safety of intrapleural perfusion with hyperthermic chemotherapy for malignant pleural effusion: a meta-analysis.

OBJECTIVE: To evaluate the efficacy and safety of intrapleural perfusion with hyperthermic chemotherapy (IPHC) in treating malignant pleural effusion (MPE). METHODS: PubMed, Embase, Cochrane Library, Chinese National Knowledge Infrastructure (CNKI), Chinese Biomedical Literature Database (CBM), VIP Chinese Science and Technology Journal Full-text Database (VP-CSJFD), and Wanfang database were searched by computer from database establishment to January 17, 2024. Relevant randomized controlled articles with IPHC as the observational group and intrapleural perfusion chemotherapy (IPC) as the control group for MPE were included. Then, the methodological quality of the included articles was evaluated and statistically analyzed using Stata 16.0. RESULTS: Sixteen trials with 647 patients receiving IPHC and 661 patients receiving IPC were included. The meta-analysis found that MPE patients in the IPHC group had a more significant objective response rate [RR = 1.31, 95%CI (1.23, 1.38), P < 0.05] and life quality improvement rate [RR = 2.88, 95%CI (1.95, 4.24), P < 0.05] than those in the IPC group. IPHC and IPC for MPE patients had similar incidence rates of asthenia, thrombocytopenia, hepatic impairment, and leukopenia. CONCLUSION: Compared with IPC, IPHC has a higher objective response rate without significantly increasing adverse reactions. Therefore, IPHC is effective and safe. However, this study is limited by the quality of the literature. Therefore, more high-quality, multi-center, large-sample, rigorously designed randomized controlled clinical studies are still needed for verification and evaluation.

Single-cell transcriptomics reveal metastatic CLDN4+ cancer cells underlying the recurrence of malignant pleural effusion in patients with advanced non-small-cell lung cancer.

BACKGROUND: Recurrent malignant pleural effusion (MPE) resulting from non-small-cell lung cancer (NSCLC) is easily refractory to conventional therapeutics and lacks predictive markers. The cellular or genetic signatures of recurrent MPE still remain largely uncertain. METHODS: 16 NSCLC patients with pleural effusions were recruited, followed by corresponding treatments based on primary tumours. Non-recurrent or recurrent MPE was determined after 3-6 weeks of treatments. The status of MPE was verified by computer tomography (CT) and cytopathology, and the baseline pleural fluids were collected for single-cell RNA sequencing (scRNA-seq). Samples were then integrated and profiled. Cellular communications and trajectories were inferred by bioinformatic algorithms. Comparative analysis was conducted and the results were further validated by quantitative polymerase chain reaction (qPCR) in a larger MPE cohort from the authors' centre (n = 64). RESULTS: The scRNA-seq revealed that 33 590 cells were annotated as 7 major cell types and further characterized into 14 cell clusters precisely. The cell cluster C1, classified as Epithelial Cell Adhesion Molecule (EpCAM)+ metastatic cancer cell and correlated with activation of tight junction and adherence junction, was significantly enriched in the recurrent MPE group, in which Claudin-4 (CLDN4) was identified. The subset cell cluster C3 of C1, which was enriched in recurrent MPE and demonstrated a phenotype of ameboidal-type cell migration, also showed a markedly higher expression of CLDN4. Meanwhile, the expression of CLDN4 was positively correlated with E74 Like ETS Transcription Factor 3 (ELF3), EpCAM and Tumour Associated Calcium Signal Transducer 2 (TACSTD2), independent of driver-gene status. CLDN4 was also found to be associated with the expression of Hypoxia Inducible Factor 1 Subunit Alpha (HIF1A) and Vascular Endothelial Growth Factor A (VEGFA), and the cell cluster C1 was the major mediator in cellular communication of VEGFA signalling. In the extensive MPE cohort, a notably increased expression of CLDN4 in cells from pleural effusion among patients diagnosed with recurrent MPE was observed, compared with the non-recurrent group, which was also associated with a trend towards worse overall survival (OS). CONCLUSIONS: CLDN4 could be considered as a predictive marker of recurrent MPE among patients with advanced NSCLC. Further validation for its clinical value in cohorts with larger sample size and in-depth mechanism studies on its biological function are warranted. TRIAL REGISTRATION: Not applicable.

Usefulness of thoracic ultrasound in the assessment of removal of indwelling pleural catheter in patients with malignant pleural effusion.

INTRODUCTION: There are no defined criteria for deciding to remove a non-functioning indwelling pleural catheter (IPC) when lung re-expansion on chest X-ray is incomplete. Chest computed tomography (chest CT) is usually used. The objective of this work is to validate the usefulness of chest ultrasound performed by a pulmonologist and by a radiologist compared to chest CT. PATIENTS AND METHODS: Prospective, descriptive, multidisciplinary and multicenter study including patients with malignant pleural effusion and non-functioning IPC without lung reexpansion. Decisions made on the basis of chest ultrasound performed by a pulmonologist, and performed by a radiologist, were compared with chest CT as the gold standard. RESULTS: 18 patients were analyzed, all of them underwent ultrasound by a pulmonologist and chest CT and in 11 of them also ultrasound by a radiologist. The ultrasound performed by the pulmonologist presents a sensitivity of 60%, specificity of 100%, PPV 100% and NPV 66% in the decision of the correct removal of the IPC. The concordance of both ultrasounds (pulmonologist and radiologist) was 100%, with a kappa index of 1. The 4 discordant cases were those in which the IPC was not located on the ultrasound. CONCLUSIONS: Thoracic ultrasound performed by an expert pulmonologist is a valid and simple tool to determine spontaneous pleurodesis and remove a non-functioning IPC, which would make it possible to avoid chest CT in those cases in which lung reexpansion is observed with ultrasonography.

Australasian Malignant PLeural Effusion (AMPLE)-4 trial: study protocol for a multi-centre randomised trial of topical antibiotics prophylaxis for infections of indwelling pleural catheters.

BACKGROUND: Malignant pleural effusion (MPE) is a debilitating condition as it commonly causes disabling breathlessness and impairs quality of life (QoL). Indwelling pleural catheter (IPC) offers an effective alternative for the management of MPE. However, IPC-related infections remain a significant concern and there are currently no long-term strategies for their prevention. The Australasian Malignant PLeural Effusion (AMPLE)-4 trial is a multicentre randomised trial that evaluates the use of topical mupirocin prophylaxis (vs no mupirocin) to reduce catheter-related infections in patients with MPE treated with an IPC. METHODS: A pragmatic, multi-centre, open-labelled, randomised trial. Eligible patients with MPE and an IPC will be randomised 1:1 to either regular topical mupirocin prophylaxis or no mupirocin (standard care). For the interventional arm, topical mupirocin will be applied around the IPC exit-site after each drainage, at least twice weekly. Weekly follow-up via phone calls or in person will be conducted for up to 6 months. The primary outcome is the percentage of patients who develop an IPC-related (pleural, skin, or tract) infection between the time of catheter insertion and end of follow-up period. Secondary outcomes include analyses of infection (types and episodes), hospitalisation days, health economics, adverse events, and survival. Subject to interim analyses, the trial will recruit up to 418 participants. DISCUSSION: Results from this trial will determine the efficacy of mupirocin prophylaxis in patients who require IPC for MPE. It will provide data on infection rates, microbiology, and potentially infection pathways associated with IPC-related infections. ETHICS AND DISSEMINATION: Sir Charles Gairdner and Osborne Park Health Care Group Human Research Ethics Committee has approved the study (RGS0000005920). Results will be published in peer-reviewed journals and presented at scientific conferences. TRIAL REGISTRATION: Australia New Zealand Clinical Trial Registry ACTRN12623000253606. Registered on 9 March 2023.

Reliably making the primary diagnosis of mesothelioma utilizing serous fluid cytology specimens: an institutional experience.

INTRODUCTION: The diagnosis of mesothelioma has historically been challenging, especially on serous fluid cytology (SFC). Distinguishing between reactive and neoplastic mesothelial cells can be difficult on cytomorphology alone. However, additional ancillary tests, such as BRCA1 associated protein-1 immunohistochemistry and fluorescence in situ hybridization for cyclin-dependent kinase inhibitor 2A deletion, can provide a sensitive and highly specific method of proving malignancy. MATERIALS AND METHODS: SFC specimens diagnosed as mesothelioma, suspicious for mesothelioma (SM), and atypical mesothelial cells (AMCs) since 2012 were identified by querying the laboratory information system. Clinical data and pathologic parameters were gathered. RESULTS: One hundred ten cases of mesothelioma, SM, and AMC were identified. Of these, 61 cases had a definitive diagnosis of mesothelioma on SFC. Average age at SFC diagnosis was 67 years (26-87 years), with most patients being male (67%). Out of the 61 cases, 11 cases (18%) had an initial diagnosis of mesothelioma made on SFC specimens, with 5 of these 11 cases being in patients that never received a histologic diagnosis of mesothelioma. Ancillary studies were utilized in all 11 cases. An initial diagnosis of metastatic mesothelioma was made on SFC in 9 cases (15%). For 6 of these 9 cases, the SFC diagnosis was the sole diagnosis of metastatic mesothelioma without a companion histologic diagnosis. In addition, 15 cases were diagnosed as SM, with 11 of these cases following a definitive mesothelioma diagnosis. Thirty-four cases were diagnosed as AMC, with 27 cases following a definitive mesothelioma diagnosis. CONCLUSIONS: The diagnosis of mesothelioma can be reliably made on SFC with the appropriate cytomorphology criteria and/or confirmatory ancillary testing.

Exploratory pilot study to characterize the immune landscapes of malignant pleural effusions and their corresponding primary tumors from patients with breast carcinoma and lung adenocarcinoma.

INTRODUCTION: Malignant pleural effusion (MPE) is a frequent complication of advanced malignancies. In this pilot study, we characterized the immune landscapes of MPEs, compared them to their primary tumor (PT) samples from breast carcinoma (BC) and lung adenocarcinoma (LADC), and tested the utility of multiplexed image technology in cytological samples. MATERIALS AND METHODS: We evaluated the immune contexture of 6 BC and 5 LADC MPEs and their PTs using 3 multiplex immunofluorescence panels. We explored the associations between sample characteristics and pleural effusion-free survival. RESULTS: No MPE samples had positive programmed death-ligand 1 expression in malignant cells, although 3 of 11 PTs has positive programmed death-ligand 1 expression (more than 1% expression in malignant cells). Overall, in LADC samples, cluster of differentiation 3 (CD3)+ T cells and CD3+CD8+ cytotoxic T cells predominated (median percentages for MPEs versus PTs: 45.6% versus 40.7% and 4.7% versus 6.6%, respectively) compared with BC. CD68+ macrophages predominated in the BC samples (medians for MPEs 61.2% versus PTs for 57.1%) but not in the LADC samples. Generally in PTs, CD3+CD8+ forkhead box P3+ T cells and the median distances from the malignant cells to CD3+CD8+Ki67+ and CD3+ programmed cell death protein 1 + T cells correlated to earlier MPE after PT diagnosis. CONCLUSIONS: The immune cell phenotypes in the MPEs and PTs were similar within each cancer type but different between BC versus LADC. An MPE analysis can potentially be used as a substitute for a PT analysis, but an expanded study of this topic is essential.

Transcriptomic Profiling of Pleural Effusions: Differences in Malignant and Infectious Fluids.

Background and Objectives: Different cellular and molecular processes are involved in the production of malignant and infectious pleural effusions. However, the underlying mechanisms responsible for these differences or their consequences remain incompletely understood. The objective of this study was to identify differences in gene expression in pleural exudates of malignant and infectious aetiology and establish the possible different biological processes involved in both situations. Materials and Methods: RNA transcriptomic analysis was performed on 46 pleural fluid samples obtained during diagnostic thoracocenteses from 46 patients. There were 35 exudates (19 malignant and 16 infectious effusions) and 11 transudates that were used as a reference control group. Differential gene expression analysis for both exudative groups was identified. An enrichment score using the Human Kegg Orthology database was used for establishing the biological processes associated with malignant and infectious pleural effusions. Results: When comparing malignant exudates with infectious effusions, 27 differentially expressed genes with statistical significance were identified. Network analysis showed ten different biological processes for malignant and for infectious pleural effusions. In malignant fluids, processes related to protein synthesis and processing predominate. In infectious exudates, biological processes in connection with ATP production prevail. Conclusions: This study demonstrates differentially expressed genes in malignant and infectious pleural effusions, which could have important implications in the search for diagnostic or prognostic biomarkers. In addition, for the first time, biological processes involved in these two causes of pleural exudates have been described.

Myelomatous pleural effusion in multiple myeloma- A rare presentation.

Multiple myeloma is a malignant plasma cell condition that mostly affects the skeletal system and bone marrow. Pleural effusions are uncommon and typically result from other conditions coexisting with multiple myeloma. Malignant myelomatous pleural effusions are rare complications of multiple myeloma, occurring in less than 1% of patients and are associated with poor prognosis having mean survival of less than 4 months. The present case report is a 41-year-old multiple myeloma patient who developed bilateral pleural effusion at a disease relapse. Chemotherapeutic regimen of cyclophosphamide, bortezomib, and dexamethasone given. Despite a positive response to treatment, the patient's condition worsened over the course of following month and he eventually passed away. Myelomatous pleural effusion indicates poor prognosis and early consideration helps in quick diagnosis and initiation of treatment which may help in improving prognosis.

Immune checkpoint inhibitor plus chemotherapy as first-line treatment for non-small cell lung cancer with malignant pleural effusion: a retrospective multicenter study.

BACKGROUND: Immune checkpoint inhibitors (ICI) combined with chemotherapy are efficacious for treating advanced non-small cell lung cancer (NSCLC); however, the effectiveness of this approach in the malignant pleural effusion (MPE) population is unclear. This study evaluated ICI plus chemotherapy in NSCLC patients with MPE. METHODS: Patients from 3 centers in China with NSCLC and MPE who received ICI plus chemotherapy (ICI Plus Chemo) or chemotherapy alone (Chemo) between December 2014 and June 2023 were enrolled. Clinical outcomes and adverse events (AEs) were compared. RESULTS: Of 155 eligible patients, the median age was 61.0 years old. Males and never-smokers accounted for 73.5% and 39.4%, respectively. Fifty-seven and 98 patients received ICI Plus Chemo or Chemo, respectively. With a median study follow-up of 10.8 months, progression-free survival (PFS) was significantly longer with ICI Plus Chemo than with Chemo (median PFS: 7.4 versus 5.7 months; HR = 0.594 [95% CI: 0.403-0.874], P = 0.008). Median overall survival (OS) did not differ between groups (ICI Plus Chemo: 34.2 versus Chemo: 28.3 months; HR = 0.746 [95% CI: 0.420-1.325], P = 0.317). The most common grade 3 or worse AEs included decreased neutrophil count (3 [5.3%] patients in the ICI Plus Chemo group vs. 5 [5.1%] patients in the Chemo group) and decreased hemoglobin (3 [5.3%] versus 10 [10.2%]). CONCLUSIONS: In patients with untreated NSCLC with MPE, ICI plus chemotherapy resulted in significantly longer PFS than chemotherapy and had a manageable tolerability profile, but the effect on OS may be limited.

Engineered lactococcus lactis intrapleural therapy promotes regression of malignant pleural effusion by enhancing antitumor immunity.

Intrapleural immunotherapies have emerged as a prominent field in treating malignant pleural effusion (MPE). Among these, bacteria-based intrapleural therapy has exerted an anti-MPE effect by immuno-stimulating or cytotoxic properties. We previously engineered a probiotic Lactococcus lactis (FOLactis) expressing a fusion protein of Fms-like tyrosine kinase 3 and co-stimulator OX40 ligands. FOLactis activates tumor antigen-specific immune responses and displays systemic antitumor efficacy via intratumoral delivery. However, no available lesions exist in the pleural cavity of patients with MPE for intratumoral administration. Therefore, we further optimize FOLactis to treat MPE through intrapleural injection. Intrapleural administration of FOLactis (I-Pl FOLactis) not only distinctly suppresses MPE and pleural tumor nodules, but also significantly extends noticeable survival in MPE-bearing murine models. The proportion of CD103+ dendritic cells (DCs) in tumor-draining lymph nodes increases three-fold in FOLactis group, compared to the wild-type bacteria group. The enhanced DCs recruitment promotes the infiltration of effector memory T and CD8+ T cells, as well as the activation of NK cells and the polarization of macrophages to M1. Programmed death 1 blockade antibody combination further enhances the antitumor efficacy of I-Pl FOLactis. In summary, we first develop an innovative intrapleural strategy based on FOLactis, exhibiting remarkable efficacy and favorable biosafety profiles. These findings suggest prospective clinical translation of engineered probiotics for managing MPE through direct administration into the pleural cavity.

Cytomorphology of metastatic malignant peripheral nerve sheath tumour present in pleural fluid: Case study and literature review.

The cytomorphology of MPNST in effusion specimens is rarely described. In this paper, the detailed cytopathological and immunohistochemical characteristics of metastatic MPNST has been described in pleural effusion. Patients' medical history and the judicious utilization of ancillary studies contribute to ensure precise cytological diagnoses. The cytomorphology of malignant peripheral nerve sheath tumour (MPNST) in effusion specimens can be diagnostically challenging. The author presents detailed cytopathological and immunohistochemical characteristics of a case of metastatic MPNST in pleural effusion.

Establishing mesothelioma patient-derived organoid models from malignant pleural effusions.

OBJECTIVES: Pleural mesothelioma is a cancer arising in the cells that line the lungs and chest wall with poor survival and poor response to first-line therapy. Organoid models of cancer can faithfully recapitulate the genetic and histopathological characteristics of individualized tumors and have potential to be used for precision medicine, however methods of establishing patient-derived mesothelioma organoids have not been well established in the published literature. MATERIALS AND METHODS: Long-term mesothelioma patient-derived organoids were established from ten malignant pleural effusion fluids. Mesothelioma patient-derived organoids were compared to the corresponding biopsy tissue specimens using immunohistochemistry labelling for select diagnostic markers and the TruSight Oncology-500 sequencing assay. Cell viability in response to the chemotherapeutic drug cisplatin was assessed. RESULTS: We established five mesothelioma patient-derived organoid cultures from ten malignant pleural effusion fluids collected from nine individuals with pleural mesothelioma. Mesothelioma patient-derived organoids typically reflected the histopathological and genomic features of patients' matched biopsy specimens and displayed cytotoxic sensitivity to cisplatin in vitro. CONCLUSION: This is the first study of its kind to establish long-term mesothelioma organoid cultures from malignant pleural effusions and report on their utility to test individuals' chemotherapeutic sensitivities ex vivo.

First-line treatment of driver gene-negative metastatic lung adenocarcinoma with malignant pleural effusion: Should chemotherapy be combined with an immune checkpoint inhibitor or bevacizumab?

Patients with metastatic lung adenocarcinoma (MLA) and malignant pleural effusion (MPE) without driver gene mutations have a poor prognosis. None of the standard treatment strategies is recommended for such patients. We retrospectively analyzed the efficacy of the first-line treatment for this specific population: standard platinum-based doublet chemotherapy (CT), CT plus an immune checkpoint inhibitor (CT plus ICI), and CT plus bevacizumab (CT plus Bev). A total of 323 eligible patients were enrolled: CT alone (n = 166), CT plus Bev (n = 72), and CT plus ICI (n = 85). Treatment efficacy assessments were performed every two cycles according to the RECIST guidelines. The endpoints were overall survival (OS) and progression-free survival (PFS). Kaplan-Meier (K‒M) curves and the log-rank test were used to compare OS and PFS. p < 0.05 was the threshold of significance (statistical software: SPSS). The median follow-up was 11.4 months (range, 2.1-49.6 months). PFS and OS in the CT plus ICI/CT plus Bev cohort were significantly longer than those in the CT group (PFS: 7.8/6.4/3.9 months, p < 0.0001; OS: 16.4/15.6/9.6 months, p < 0.0001, respectively). CT plus Bev had better PFS and OS than CT plus ICI/CT in PD-L1 < 1% patients (PFS: 8.4/5.0/3.8 months, p < 0.0001; OS: 15.6/12.9/9.3 months, p < 0.0001). Among patients with PD-L1 1-49%, CT plus ICI led to a longer PFS and OS (PFS: 8.9/5.8/4.2 months, p = 0.009; OS: 24.2/18.8/11.5 months, p = 0.03). In the cohort with PD-L1 ≥ 50%, CT plus ICI was still the best first-line treatment (PFS: 19.7/13.8/9.6 months, p = 0.033; OS: 27.2/19.6/14.9 months, p = 0.047). In driver gene-negative MLA with MPE, CT plus Bev or ICI better controlled MPE and significantly prolonged survival compared to CT alone. PD-L1 expression (negative/positive) may be a key factor influencing the choice of CT plus Bev or ICI.

Detection of effusion tumor cells under different storage and processing conditions.

BACKGROUND: Circulating tumor cells (CTCs) shed into blood provide prognostic and/or predictive information. Previously, the authors established an assay to detect carcinoma cells from pleural fluid, termed effusion tumor cells (ETCs), by employing an immunofluorescence-based CTC-identification platform (RareCyte) on air-dried unstained ThinPrep (TP) slides. To facilitate clinical integration, they evaluated different slide processing and storage conditions, hypothesizing that alternative comparable conditions for ETC detection exist. METHODS: The authors enumerated ETCs on RareCyte, using morphology and mean fluorescence intensity (MFI) cutoffs of >100 arbitrary units (a.u.) for epithelial cellular adhesion molecule (EpCAM) and <100 a.u. for CD45. They analyzed malignant pleural fluid from three patients under seven processing and/or staining conditions, three patients after short-term storage under three conditions, and seven samples following long-term storage at -80°C. MFI values of 4',6-diamidino-2-phenylindol, cytokeratin, CD45, and EpCAM were compared. RESULTS: ETCs were detected in all conditions. Among the different processing conditions tested, the ethanol-fixed, unstained TP was most similar to the previously established air-dried, unstained TP protocol. All smears and Pap-stained TPs had significantly different marker MFIs from the established condition. After short-term storage, the established condition showed comparable results, but ethanol-fixed and Pap-stained slides showed significant differences. ETCs were detectable after long-term storage at -80°C in comparable numbers to freshly prepared slides, but most marker MFIs were significantly different. CONCLUSIONS: It is possible to detect ETCs under different processing and storage conditions, lending promise to the application of this method in broader settings. Because of decreased immunofluorescence-signature distinctions between cells, morphology may need to play a larger role.

Clinical impact of pleural fluid carcinoembryonic antigen on therapeutic strategy and efficacy in lung adenocarcinoma patients with malignant pleural effusion.

BACKGROUND/AIMS: Epidermal growth factor receptor (EGFR) mutation is important in determining the treatment strategy for advanced lung cancer patients with malignant pleural effusion (MPE). Contrary to serum carcinoembryonic antigen (S-CEA) levels, the associations between pleural fluid CEA (PF-CEA) levels and EGFR mutation status as well as between PF-CEA levels and treatment efficacy have rarely been investigated in lung adenocarcinoma patients with MPE. METHODS: This retrospective study enrolled lung adenocarcinoma patients with MPE and available PF-CEA levels and EGFR mutation results. The patients were categorized based on PF-CEA levels: < 10 ng/mL, 10-100 ng/mL, 100-500 ng/mL, and ≥ 500 ng/mL. The association between PF-CEA levels and EGFR mutation status as well as their therapeutic impact on overall survival was compared among the four groups. RESULTS: This study included 188 patients. PF-CEA level was found to be an independent predictor of EGFR mutation but not S-CEA level. The EGFR mutation rates were higher as the PF-CEA levels increased, regardless of cytology results or sample types. Among EGFR-mutant lung adenocarcinoma patients receiving EGFR-tyrosine kinase inhibitor (TKI) treatment, those with high PF-CEA levels had significantly better survival outcomes than those with low PF-CEA levels. CONCLUSION: High PF-CEA levels were associated with high EGFR mutation rate and may lead to a favorable clinical outcome of EGFR-TKI treatment in EGFR-mutant lung adenocarcinoma patients with MPE. These findings highlight the importance of actively investigating EGFR mutation detection in patients with suspected MPE and elevated PF-CEA levels despite negative cytology results.

Metastatic upper tract urothelial carcinoma with nest-like features presenting as malignant pleural effusion.

Metastatic urothelial carcinoma is a rare cause of pleural effusions. We report a case of urothelial carcinoma of the upper urinary tract in an oldest-old male patient, a smoker, with situs inversus totalis, that presented uniquely with malignant pleural effusion at presentation without evidence of a primary tumor on imaging. Cytological smears of the massive left pleural effusion revealed epithelioid neoplastic cells arranged in short cords, small-to-large clusters, and raspberry-like morules, mimicking mesothelioma; cell block preparations highlighted the presence of tubules and nest-like structures. The tumor cells showed a high nuclear-to-cytoplasmic ratio, nuclear grooves, and mitotic figures. Cytomorphologic features coupled with the immunophenotype of neoplastic cells (p63, GATA3, and uroplakin II positive) allowed the diagnosis of metastatic urothelial carcinoma and a possible nested subtype. These findings were supported by a total body computed tomography (CT) showing no evidence of a mass in the bladder or elsewhere in the urinary tract but a concentric parietal thickening of the proximal left ureter, suggesting malignancy. To our knowledge, a malignant effusion as a primary manifestation of urothelial carcinoma with nest-like features originating in the upper urinary tract has never been described previously. Our case focuses on the value of cell block in the working-up of neoplastic effusions by revealing the architectural pattern of an uncommon malignancy and the correlation between cytopathology and imaging gross findings to reach an accurate diagnosis.