Malignant pleural mesothelioma: Description of pleural decortication and hyperthermic chemotherapy technique in multimodal therapy.

The current treatment for mesothelioma, in selected cases, consists of extended pleurodecortication and intrathoracic hyperthermic chemotherapy. This technique is laborious and detailed and must be followed step by step to achieve good results. We present the case of a patient with epithelioid mesothelioma meeting surgical criteria who underwent the mentioned technique, experiencing an adequate postoperative period and an early discharge. This experience demonstrates that the technique is safe when performed in centres with experience and the means to address this complex pathology.

Identifying malignant mesothelioma by a pathological survey using the São Paulo state hospital cancer registry, Brazil.

OBJECTIVE: To review the pathological diagnosis of possible cases and/or hidden cases of malignant mesothelioma (MM) between 2000 and 2012 using the Hospital-Based Cancer Registry database in the state of São Paulo, Brazil. METHODS: Possible cases were retrieved by assessing the database. Inclusion criteria were being older than 30 years of age and having ICD-O-3 topography and morphology codes related to MM. A board of expert pathologists reviewed the pathology reports and requested paraffin blocks in cases that demanded revision. After staining with calretinin, D2-40, WT-1 (as positive MM markers) and Ber-EP4 and MOC31 (as negative MM markers), cases were divided and studied independently by a pair of pathologists to confirm or discard the diagnosis of MM. RESULTS: Our sample comprised 482 cases from 25 hospitals, and 130 needed further histological revision. We received 73 paraffin blocks with adequate material. After board analysis, there were 9 cases with a definitive diagnosis of MM, improving the diagnostic rate in 12%. Two cases of previously diagnosed MM were discarded by review. CONCLUSIONS: Our results confirm that part of MM underdiagnosis and underreporting in Brazil is due to incomplete or mistaken pathological diagnosis.

Pleural mesothelioma from fluoro-edenite exposure: PACAP and PAC1 receptor. A preliminary report.

Pleural mesothelioma is a devastating malignancy primarily associated with asbestos exposure. However, emerging evidence suggests that exposure to fluoro-edenite fibers, a naturally occurring mineral fiber, can also lead to the development of pleural mesothelioma. In this study, based on the hypothesis that pituitary adenylate cyclase-activating polypeptide (PACAP) and PACAP-preferring receptor (PAC1R) expressions could be dysregulated in pleural mesothelioma samples and that they could potentially act as diagnostic or prognostic biomarkers, we aimed to investigate the immunohistochemical expression of PACAP and PAC1R in pleural biopsies from patients with pleural mesothelioma exposed to fluoro-edenite fibers. A total of 12 patients were included in this study, and their biopsies were processed for immunohistochemical analysis to evaluate the expression of PACAP and its receptor. The study revealed a correlation between the overexpression of PACAP and PAC1R and shorter overall survival in patients with malignant mesothelioma. These findings suggest that PACAP and PAC1R expression levels could serve as potential prognostic biomarkers for malignant mesothelioma. Furthermore, the immunohistochemical analysis of PACAP and PAC1R may provide valuable information for clinicians to guide therapeutic decisions and identify patients with poorer prognosis.

High mobility group box 1 mediates inflammatory responses in malignant peritoneal mesothelioma.

BACKGROUND: Serum high mobility group box 1 (HMGB1) serves as a diagnostic biomarker for malignant peritoneal mesothelioma (MPM) patients, yet its diagnostic significance within MPM tumor tissues remains uncertain. This study aims to elucidate the roles of HMGB1 in MPM. METHODS: HMGB1 expression analysis was conducted in both tumor and adjacent non-cancerous tissues collected from MPM patients. The two-year follow-up of MPM patients commenced from the diagnosis date. Inflammatory cytokine analysis was performed on these tissues, and Pearson correlation coefficient analysis was applied to examine variable relationships. In vitro assays included constructing an HMGB1 knockdown cell line, assessing cell viability, apoptosis, and inflammatory cytokine levels to delineate HMGB1's roles in MPM. RESULTS: HMGB1 overexpression was observed in MPM tumor tissues, particularly in stages III-IV. Diagnostic implications of HMGB1 for MPM were evident, augmenting its diagnostic value. HMGB1 overexpression correlated with diminished survival rates. Positive correlations existed between inflammatory cytokines and HMGB1 in MPM tumor tissues and cell lines. Suppression of HMGB1 regulated cell growth and apoptosis in MPM cell lines. CONCLUSION: HMGB1 exhibits diagnostic potential for MPM and modulates inflammatory responses within the disease context.

Diagnostic performance of immunohistochemistry markers for malignant pleural mesothelioma diagnosis and subtypes. A systematic review and meta-analysis.

BACKGROUND: Malignant pleural mesothelioma (MPM) poses diagnostic challenges due to its resemblance to benign pleural pathologies and different histological subtypes. Several immunohistochemistry markers have been employed to aid in accurate diagnosis. METHODS: The present systematic review and meta-analysis aimed to assess the diagnostic performance of various immunohistochemistry markers in malignant pleural mesothelioma diagnosis and its histological subtypes. Following the PRISMA guidelines, we systematically searched the literature for articles on using different immunohistochemical markers in MPM and its histological subtypes. EMBASE, LILACS, MEDLINE, and Virtual Health Library were searched for studies published up to August 2023. We used the QUADAS-2 (Quality Assessment of Diagnostic Accuracy Studies) criteria to assess the quality of the included articles. Meta-analyses were performed to determine prevalence using a random-effects model. RESULTS: 103 studies met the inclusion criteria, comprising a diverse range of immunohistochemistry markers. EMA and desmin-loss exhibited high sensitivity (96% and 92%, respectively) in distinguishing malignant pleural mesothelioma from benign pleural pathologies. Specificity was notably high for both BAP1-loss and survivin expression at 100%. Subtype-specific analyses demonstrated that EMA and HEG1 were sensitive markers for epithelioid mesothelioma, while GLUT1 showed high sensitivity for sarcomatoid mesothelioma. In cases comparing epithelioid mesothelioma and lung adenocarcinoma, CAM5.2 and calretinin displayed high sensitivity, while WT1 and BAP1-loss demonstrated exceptional specificity for malignant epithelioid mesothelioma. In the case of sarcomatoid mesothelioma and sarcomatoid lung carcinoma, GATA3 exhibited the most heightened sensitivity, while GATA3 and D2-40 displayed the best specificity for sarcomatoid malignant mesothelioma diagnosis. CONCLUSION: Immunohistochemistry markers are essential in accurately diagnosing malignant pleural mesothelioma and its histological subtypes. This systematic review and meta-analysis provide a comprehensive insight into the diagnostic performance of these markers, facilitating their potential clinical utility in the discrimination of malignant pleural mesothelioma from other pleural pathologies and the differentiation of malignant pleural mesothelioma subtypes.

Risk factors influencing postoperative pleural empyema in patients with pleural mesothelioma: a retrospective single-centre analysis.

OBJECTIVES: Postoperative empyema is a severe, potentially lethal complication also present, but poorly studied in patients undergoing surgery for pleural mesothelioma. We aimed to analyse which perioperative characteristics might be associated with an increased risk for postoperative empyema. METHODS: From September 1999 to February 2023 a retrospective analysis of consecutive patients undergoing surgery for pleural mesothelioma at the University Hospital of Zurich was performed. Uni- and multivariable logistic regression was used to identify associated risk factors of postoperative empyema after surgery. RESULTS: A total of 400 PM patients were included in the analysis, of which n = 50 patients developed empyema after surgery (12.5%). Baseline demographics were comparable between patients with (Eyes) and without empyema (Eno). 39% (n = 156) patients underwent extrapleural pneumonectomy (EPP), of whom 22% (n = 35) developed postoperative pleural empyema; 6% (n = 15) of the remaining 244 patients undergoing pleurectomy and decortication (n = 46), extended pleurectomy and decortication (n = 114), partial pleurectomy (n = 54) or explorative thoracotomy (n = 30) resulted in postoperative empyema. In multivariable logistic regression analysis, EPP (odds ratio 2.8, 95% confidence interval 1.5-5.4, P = 0.002) emerged as the only risk factor associated with postoperative empyema when controlled for smoking status. Median overall survival was significantly worse for Eyes (16 months, interquartile range 5-27 months) than for Eno (18 months, interquartile range 8-35 months). CONCLUSIONS: Patients undergoing EPP had a significantly higher risk of developing postoperative pleural empyema compared to patients undergoing other surgery types. Survival of patients with empyema was significantly shorter.

YAP/TAZ-TEAD signalling axis: A new therapeutic target in malignant pleural mesothelioma.

The Hippo signalling pathway, a highly conserved signalling cassette, regulates organ size by controlling cell growth, apoptosis and stem cell self-renewal. The tumourigenic potential of this pathway is largely attributed to the activity of YAP/TAZ, which activate the TEAD1-4 transcription factors, leading to the expression of genes involved in cell proliferation and suppression of cell death. Aberrant regulation of the YAP/TAZ-TEAD signalling axis is commonly observed in malignant pleural mesothelioma (MPM), an insidious neoplasm of the pleural tissue that lines the chest cavity and covers the lungs with poor prognosis. Given the limited effectiveness of current treatments, targeting the YAP/TAZ-TEAD signalling cascade has emerged as a promising therapeutic strategy in MPM. Several inhibitors of the YAP/TAZ-TEAD signalling axis are presently undergoing clinical development, with the goal of advancing them to clinical use in the near future.

Genomic characterization and detection of potential therapeutic targets for peritoneal mesothelioma in current practice.

Peritoneal mesothelioma (PeM) is an aggressive tumor with limited treatment options. The current study aimed to evaluate the value of next generation sequencing (NGS) of PeM samples in current practice. Foundation Medicine F1CDx NGS was performed on 20 tumor samples. This platform assesses 360 commonly somatically mutated genes in solid tumors and provides a genomic signature. Based on the detected mutations, potentially effective targeted therapies were identified. NGS was successful in 19 cases. Tumor mutational burden (TMB) was low in 10 cases, and 11 cases were microsatellite stable. In the other cases, TMB and microsatellite status could not be determined. BRCA1 associated protein 1 (BAP1) mutations were found in 32% of cases, cyclin dependent kinase inhibitor 2A/B (CDKN2A/B) and neurofibromin 2 (NF2) mutations in 16%, and ataxia-telangiectasia mutated serine/threonine kinase (ATM) in 11%. Based on mutations in the latter two genes, potential targeted therapies are available for approximately a quarter of cases (i.e., protein kinase inhibitors for three NF2 mutated tumors, and polyADP-ribose polymerase inhibitors for two ATM mutated tumors). Extensive NGS analysis of PeM samples resulted in the identification of potentially effective targeted therapies for about one in four patients. Although these therapies are currently not available for patients with PeM, ongoing developments might result in new treatment options in the future.

The presence of erionite in North American geologies and the estimated mesothelioma potency by region.

OBJECTIVE: Erionite is a naturally occurring fibrous mineral found in soils in some geographical regions. Known for its potency for causing mesothelioma in the Cappadocia region of Turkey, the erionite fiber has attracted interest in the United States due to its presence in a band of rock that extends from Mexico to Montana. There are few toxicology studies of erionite, but all show it to have unusually high chronic toxicity. Despite its high potency compared to asbestos fibers, erionite has no occupational or environmental exposure limits. This paper takes what has been learned about the chemical and physical characteristics of the various forms of asbestos (chrysotile, amosite, anthophyllite, and crocidolite) and predicts the potency of North American erionite fibers. MATERIALS AND METHODS: Based on the fiber potency model in Korchevskiy et al. (2019) and the available published information on erionite, the estimated mesothelioma potency factors (the proportion of mesothelioma mortality per unit cumulative exposure (f/cc-year)) for erionites in the western United States were determined. RESULTS AND DISCUSSION: The model predicted potency factors ranged from 0.19 to 11.25 (average ∼3.5), depending on the region. For reference, crocidolite (the most potent commercial form of asbestos) is assigned a potency factor ∼0.5. CONCLUSION: The model predicted mesothelioma potency of Turkish erionite (4.53) falls in this same range of potencies as erionite found in North America. Although it can vary by region, a reasonable ratio of average mesothelioma potency based on this model is 3,000:500:100:1 comparing North American erionite, crocidolite, amosite, and chrysotile (from most potent to least potent).

Prognostic significance of inflammation scores in malignant mesothelioma.

OBJECTIVE: The relationship between inflammatory markers and survival in many cancers has been investigated previously. Inflammatory markers may also offer the possibility of predicting surveillance in patients with malignant mesothelioma. Our study seeks to enhance comprehension of how variables such as the nutritional status and inflammation indices of malignant mesothelioma patients impact the disease's progression and prognosis. PATIENTS AND METHODS: This study included patients who were treated at the Erciyes University Medical Oncology Clinic between 2010 and 2022 and diagnosed with malignant mesothelioma. This is a retrospective single-center cohort study. Receiver Operating Characteristic (ROC) analysis was applied to determine the inflammation markers' optimal cut-off values with high sensitivity and specificity. Patients were categorized based on these values. The differences in overall survival (OS) and progression-free survival (PFS) between categorized groups were assessed using Log-rank curves and Kaplan-Meier tests. Multivariate analysis was performed using Cox regression analysis on statistically significant data. The relationship between inflammation markers and malignant mesothelioma survival was evaluated. RESULTS: There are 115 patients in this study. Pre-treatment high neutrophil to lymphocyte ratio (NLR) (HR: 1.34, 95% CI: 1.12-2.83, p=0.04), high pan-immune inflammation value (PIIV) (HR: 2.01, 95% CI: 1.32-4.79, p=0.03), and high systemic inflammation response index (SIRI) (HR: 1.34, 95% CI: 1.2-2.78, p=0.04) were associated with poor OS. Conversely, high advanced lung cancer inflammation index (ALI) (HR: 0.73, 95% CI: 0.53-0.84, p=0.03) and high hemoglobin-albumin-lymphocyte and platelet (HALP) (HR: 0.67, 95% CI: 0.23-0.78, p=0.02) were associated with favorable survival. CONCLUSIONS: Our study investigated the prognostic value of various inflammation markers in malignant mesothelioma patients and suggests that composite formulas like NLR, PIIV, SIRI, ALI, and HALP that incorporate CBC cells and nutritional parameters like albumin, height, and weight could more consistently and accurately predict malignant mesothelioma prognosis.

Asbestos ban policies and mesothelioma mortality in Greece.

BACKGROUND: Malignant mesothelioma is a rare form of cancer that mostly affects the pleura and has a strong link to asbestos exposure. Greece banned the use of asbestos in 2005, however, the public was already aware of this substance in the 1980s. This research aims to present an overview of Greece's mesothelioma age-standardized mortality rates (ASMR) from 1983 to 2019 by age, gender, and geographic region and to determine whether the actions to ban asbestos impacted these rates. METHODS: Data were retrieved by the Hellenic Statistical Authority (HSA) from death certificates that mentioned mesothelioma as the cause of death from 1983 to 2019 with details on the residence, gender, and age. Statistical analysis was performed using PRISM 6.0 software, a two-way ANOVA test, Trend analysis was conducted using Joinpoint Regression Program 5.0 software. The linear and non-linear model was used to calculate the age-standardized rates of annual percentage change (APC) and its 95% confidential interval (95% CI). RESULTS: From 1983 to 2019, 850 total mesothelioma deaths were recorded, the majority of whom were males (634). A rate of 74.6% accounts for males and 25.4% for females, and the ratio of Males: Females was 3:1. Males' ASMR and the whole population's ASMR reached their highest levels in 2011 (0.93/100000person-years and 0.53/100000person-years, respectively). To look for potential changes between the first two decades of the 21st century, we compared the mean ASMR of each geographic region in Greece between two different 10-year subperiods (2000-2009 and 2010-2019). Except for Epirus, all regions of Greece had elevated regional ASMRs, particularly in those with the highest asbestos deposits. Notably, the ASMR in Epirus decreased from 0.54/100000person-years (2000-2009) to 0.31/100000person-years (2010-2019). After 2011, the ASMR for men and the general population stabilized. This stability is important since mesothelioma in men is associated with occupational asbestos exposure. The intriguing discovery of a lower ASMR in Epirus emphasizes the need to raise awareness of the condition and implement effective public health measures. CONCLUSIONS: In Greece, the annual ASMR for males and the whole population reached its highest level in 2011, which is positive and encouraging and may be a sign that the rate will stabilize during the following years. Moreover, this study showed that the actions made in the 1980s regarding public awareness and surveillance directly impacted the decrease in Epirus rates. Future research, continual awareness, information, and recording are needed to monitor the mesothelioma epidemic. The possible benefit of a mesothelioma registry and the epidemiological surveillance of asbestos-related diseases, particularly mesothelioma mortality, need to be addressed. TRIAL REGISTRATION: Not applicable.

Low Exposures to Amphibole or Serpentine Asbestos in Germline Bap1-mutant Mice Induce Mesothelioma Characterized by an Immunosuppressive Tumor Microenvironment.

Asbestos and BAP1 germline mutations are risk factors for malignant mesothelioma (MM). While it is well accepted that amphibole asbestos is carcinogenic, the role of serpentine (chrysotile) asbestos in MM has been debated. To address this controversy, we assessed whether minimal exposure to chrysotile could significantly increase the incidence and rate of MM onset in germline Bap1-mutant mice. With either crocidolite or chrysotile, and at each dose tested, MMs occurred at a significantly higher rate and earlier onset time in Bap1-mutant mice than in wild-type littermates. To explore the role of gene-environment interactions in MMs from Bap1-mutant mice, we investigated proinflammatory and protumorigenic factors and the tumor immune microenvironment (TIME). IHC and immunofluorescence staining showed an increased number of macrophages in granulomatous lesions and MMs. The relative number of CD163-positive (CD163+) M2 macrophages in chrysotile-induced MMs was consistently greater than in crocidolite-induced MMs, suggesting that chrysotile induces a more profound immunosuppressive response that creates favorable conditions for evading immune surveillance. MMs from Bap1-mutant mice showed upregulation of CD39/CD73-adenosine and C-C motif chemokine ligand 2 (Ccl2)/C-C motif chemokine receptor 2 (Ccr2) pathways, which together with upregulation of IL6 and IL10, promoted an immunosuppressive TIME, partly by attracting M2 macrophages. Interrogation of published human MM RNA sequencing (RNA-seq) data implicated these same immunosuppressive pathways and connections with CD163+ M2 macrophages. These findings indicate that increased M2 macrophages, along with upregulated CD39/CD73-adenosine and Ccl2/Ccr2 pathways, contribute to an immunosuppressive TIME in chrysotile-induced MMs of Bap1-mutant mice, suggesting that immunotherapeutic strategies targeting protumorigenic immune pathways could be beneficial in human BAP1 mutation carriers who develop MM. SIGNIFICANCE: We show that germline Bap1-mutant mice have enhanced susceptibility to MM upon minimal exposure to chrysotile asbestos, not only amphibole fibers. Chrysotile induced a more profound immune tumor response than crocidolite in Bap1-mutant mice by upregulating CD39/CD73-adenosine and Ccl2/Ccr2 pathways and recruiting more M2 macrophages, which together contributed to an immunosuppressive tumor microenvironment. Interrogation of human MM RNA-seq data revealed interconnected immunosuppressive pathways consistent with our mouse findings.

Oncolytic adenoviruses and immunopeptidomics: a convenient marriage.

Oncolytic viruses (OVs) are biological therapeutic agents that selectively destroy cancer cells while sparing normal healthy cells. Besides direct oncolysis, OV infection induces a proinflammatory shift in the tumor microenvironment and the release of tumor-associated antigens (TAAs) that might induce an anti-tumor immunity. Due to their immunostimulatory effect, OVs have been explored for cancer vaccination against specific TAAs. However, this approach usually requires genetic modification of the virus and the production of a new viral vector for each target, which is difficult to implement for low prevalent antigens. In a recent study, Chiaro et al. presented an elegant proof of concept on how to implement the PeptiCRAd vaccination platform to overcome this limitation for the treatment of mesothelioma. Authors showed the feasibility of identifying immunogenic TAAs in human mesothelioma and using them to coat oncolytic adenovirus particles. The result was a customized virus-based cancer vaccine that circumvents time and resource-consuming steps incurred from genetically engineering viruses. Although some questions remain to be addressed, this interesting approach suggests novel strategies for personalized cancer medicine using oncolytic virotherapy.

Diagnosis and treatment of malignant retroperitoneal mesothelioma: A case report.

RATIONALE: Malignant peritoneal mesothelioma (MPM) is a rare clinical disease. Although there are several reports describing intraperitoneal mesothelioma of the lung, liver, and intestine, retroperitoneal mesothelioma is, to our knowledge, very rare and rarely reported. In recent years, our best clinical protocols for the treatment and diagnosis of retroperitoneal mesothelioma have not been proven and the diagnosis and treatment are challenging. PATIENT CONCERNS: A 37-year-old Chinese woman complained of bilateral low back pain for a month, with obvious symptoms of low back pain on the left side. To treat low back pain, retroperitoneal masses were found during physical examination. The patient consulted a urological specialist for further treatment. DIAGNOSIS: After the operation, pathological biopsy confirmed retroperitoneal epithelioid diffuse mesothelioma. INTERVENTIONS: After exclusion of surgical contraindications, the patient underwent laparoscopic retroperitoneal lesion resection under tracheal intubation and general anesthesia, and the operation was successful. OUTCOMES: On the tenth day after surgery, the patient vital signs were stable, and he was discharged. LESSONS: Patients with malignant peritoneal mesothelioma may have no typical clinical symptoms, and the diagnosis is based on pathological and immunohistochemical examination. In selected patients, surgical cell reduction and intraoperative intraperitoneal heat chemotherapy have become the first choice of treatment, which can achieve ideal therapeutic effects and prolong survival.

[Expression and prognostic significance of KAP1 gene in malignant pleural mesothelioma].

Objective: To explore the expression of KAP1 (KRAB-associated protein 1, KAP1) in Malignant pleural mesothelioma (MPM) based on the cancer genome atlas (TCGA) and clinical trials. And elucidate the correlation between the expression of KAP1 and the clinical pathological parameters of patients with MPM and its prognosis. Methods: In April 2022, Based on the second generation KAP1mRNA sequencing data and clinicopathological data of MPM patients downloaded from TCGA database, the correlation between KAP1mRNA expression and clinical parameters was analyzed, and the correlation between KAP1 protein expression and clinicopathological parameters and its prognostic value were analyzed based on Chuxiong data set cohort clinical samples. The expression of KAP1 mRNA in MPM samples and matched normal tumor adjacent tissues was detected by qRT-PCR, and the expression of KAP1 protein in MPM and normal pleural tissues was detected by immunohistochemistry and Westernblotting. To construct a Kaplan-Meier model to explore the effect of KAP1 expression on the prognosis of MPM patients, and to analyze the prognostic factors of MPM patients by Cox regression. Results: qRT-PCR and Western blotting detection showed that the expression levels of KAP1 gene in four different MPM cells (NCI-H28, NCI-H2052, NCI-H2452, and MTSO-211H) were significantly higher than those in normal pleural mesothelial cells Met-5A. qRT-PCR, Western blotting and IHC results demonstrated that the mRNA and protein expression levels of KAP1 in MPM tissues was significantly higher than that in matching normal mesothelial tissues, and the expression level of KAP1 protein was correlated with TP 53 protein expression levels and serum CEA levels (P<0.05) . The mRNA expression level was significantly correlated with the prognosis, The overall survival time of mesothelioma patients with high KAP1mRNA expression was significantly shorter (HR=3.7, Logrank P<0.001) . Tumor type, age and the mRNA expression were related to the prognosis of MPM patients (P<0.05) . Multivariate analysis showed that tumor type and KAP1 mRNA expression level were independent prognostic factors of MPM patients (P<0.05) . Conclusion: In this study, TCGA database and Chuxiong cohort experiment samples were used to collect the relevant information of KAP1 expression in malignant melanoma tissues. It was confirmed that KAP1 is highly expressed in MPM tissues. The mRNA expression level and pathological type are correlated with the prognosis of patients.

Checkpoint inhibitor immunotherapy induced inflammatory arthritis secondary to Nivolumab and Ipilimumab: a pediatric first.

BACKGROUND: Immune checkpoint inhibitors (ICIs) have expanded the arsenal of cancer therapeutics over the last decade but are associated with a spectrum of immune-related adverse events (irAEs), including inflammatory arthritis. While these complications are increasingly recognized in the adult population, no cases of inflammatory arthritis irAEs have been reported in the pediatric literature. CASE PRESENTATION: A 14-year-old female with metastatic epithelioid mesothelioma was referred to the pediatric rheumatology clinic after developing progressive inflammatory joint pain in her bilateral shoulders, hips, and small joints of hands following the second cycle of Nivolumab and Ipilimumab. Initial examinations showed bilateral shoulder joint line tenderness, positive FABERs test bilaterally, tenderness over bilateral greater trochanters, and bilateral second PIP effusions. Her serological profile was notable for positive HLA-B27, positive anti-CCP, negative Rheumatoid Factor, and negative ANA. PET-CT scan performed for disease response following immunotherapy showed symmetric increased metabolic activity primarily involving the supraspinatus, gluteus medius and minimus, and semimembranosus tendon insertions. Her presentation was consistent with a grade 1 irAE that worsened to a grade 2 irAE despite NSAID therapy, prompting a short course of oral prednisolone. She achieved clinical remission of her mesothelioma following six cycles of Nivolumab and Ipilimumab and her inflammatory arthritis was controlled on Celebrex monotherapy. CONCLUSIONS: To our knowledge, this is the first pediatric case of ICI-induced inflammatory arthritis and enthesitis. This case highlights the importance of increasing awareness of diagnosis and management of irAEs in children.

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.