The clinical data, diagnostic procedures and survival are reported in 19 cases diagnosed as malignant peritoneal mesothelioma. All patients were men and 74% had an occupational exposure to asbestos, whereas in 26% no information about asbestos exposure was available. The median interval between asbestos exposure and the diagnosis appeared to be 44.7 years (range 18–49 years). The most common presenting symptoms were abdominal pain, weight loss and dysphagia. Most patients presented with a large amount of ascites. In the majority of patients no therapy except pain relief was given and the median survival from the time of diagnosis was 6 months (range: 0–29 months). Some patients received surgery or chemotherapy, which however did not prolong survival. Only in 2 patients survival exceeded 1 year, although these patients did not receive therapy. The autopsy findings of some patients showed that there were positive abdominal lymph nodes in 2 of them, while in no case positive thoracic lymph nodes were found. The relative short survival period from the time of the first diagnosis in contrast to malignant pleural mesotheliomas is probably the reason for the absence of distant metastases. In this series only in a minority of patients cytology of the ascites was positive and often a laparotomy had to be done. Since cytologic specimens are often negative, we suggest that in patients suspected of a malignant peritoneal mesothelioma, laparoscopy with directed biopsies is the diagnostic procedure of first choice.

The identification of malignant mesothelial cells in cytological smears prepared from serous effusions is still hampered by the lack of features specific for mesothelial differentiation. We examined the diagnostic value of collagen cores within clusters of tumour cells in cytological smears prepared from effusions from 43 patients with malignant mesothelioma and of 62 cases of metastatic adenocarcinoma. In Giemsa-stained smears collagen cores were detected in 51% of the cases of malignant mesothelioma and in none of the smears with metastatic adenocarcinoma. Using the Azan stain, collagen cores were detected in 64% of the malignant mesotheliomas and 4% of the adenocarcinomas. Immunoelectron microscopy demonstrated that the collagen cores are largely composed of collagen type III fibrils and some elastin embedded in a homogenous extracellular matrix. It can be concluded that the presence of collagen cores within clusters of tumour cells is highly suggestive of mesothelial differentiation and a common finding in malignant mesothelioma.

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Background:The interferon (IFN) pathway is a complex system with multiple proteins and diverse downstream effects on gene and protein expression. IFNs have been implicated in multiple RMDs. Despite significant potential, IFN assays have not progressed into clinical practice.Objectives:To perform a SLR on IFN assays in RMDs and propose a consensus terminology.Methods:OvidMedline, Embase and Web of Science were searched for reports of IFN and RMDs up to October 2019. Information about the properties of assays measuring type I IFN and measures of truth were extracted and summarised. Terminology was agreed through an interactive consensus process with reference to the existing evidence.Results:10037 abstracts were identified. 275 fulfilled eligibility criteria, and were used for data extraction. Some used more than one technique to measure IFN-I pathway activation. Hence, 275 papers generated data on 393 methods. There was great heterogeneity in the methods used and presentation of results. IFN-I pathway activation was measured using: qPCR (n=121), immunoassays (n=101), microarray (n=69), reporter cell assay (n=38), DNA methylation (n=14), flow cytometry (n=14), cytopathic effect assay (n=11), RNA sequencing (n=9), Plaque reduction assay (n=8), Nanostring (n=5), bisulphite sequencing (n=3). All papers fulfilled Face Validity. Due to lack of gold standard for IFN-I pathway activation, evidence of criterion validity was variable. Concurrent validity was presented for n=150 assays. The terminology used to describe aspects of type I IFN pathway activation was not consistent, so a consensus terminology for IFN research (Table 1) was proposed by the taskforce.Table 1.Consensus terminologyTermAbbreviationDefinitionInterferonIFNProteins with anti-viral activity; IFNs are mediators of an anti-viral response. They belong to the Type I, Type II and Type III IFN families.Type I interferonIFN-IThe IFNs alpha, beta, omega, kappa, epsilon, secreted by any nucleated cell, and binding to the IFNAR, which is expressed on any nucleated cell.Type II interferonIFN-IIIFN gamma, mostly secreted by T cells, binding to the IFNGR, which is expressed on most leucocytes.Type III interferonIFN-IIIIFN lambda, which are structurally more similar to IL-10 but share downstream signalling and gene expression with IFN-I.Interferon-stimulated genesISGsGenes whose expression is known to be upregulated by any kind of IFN. Individual ISGs may not exclusively represent Type I IFN pathway activation.Type I Interferon pathway activationAny evidence for function of the components of the Type I IFN pathway. This includes: secretion of a Type I IFN protein, binding to the IFNAR, initiation of JAK/STAT signalling pathways, expression of IFN-stimulated genes, expression of IFN-stimulated proteins.Type I interferon pathway assayAn assay measuring one or more components of the Type I IFN pathway at a molecular or functional level.Interferon stimulated gene expression signatureA qualitative description of coordinated expression of a set of ISGs that is indicative of Type I IFN pathway activation.Interferon stimulated gene expression scoreA quantitative variable derived from expression of a defined set of ISGs that is indicative of Type I IFN pathway activation.Interferon stimulated protein scoreA variable derived from expression of a defined set of soluble biomarkers known to be upregulated by IFN, although not specific for Type I IFN.InterferonopathyMonogenic diseases in which there is constitutive Type I IFN pathway activation with a causal role in pathology. The clinical picture may resemble rheumatic musculoskeletal diseases. However, most diseases with IFN pathway activation are not Interferonopathies.Conclusion:Diverse methods have been reported as IFN assays and these differ in what elements of type IFN-I pathway activation they measure. The taskforce consensus terminology on type I IFN reporting should be considered for research and clinical applications.Disclosure of Interests:Agata Burska: None declared, Javier Rodriguez Carrio: None declared, Philip G Conaghan: None declared, Willem A Dik: None declared, Robert Biesen: None declared, Maija-leena Eloranta: None declared, Giulio Cavalli: None declared, Marianne Visser: None declared, Dimitrios Boumpas: None declared, George Bertsias: None declared, Marie Wahren-Herlenius: None declared, Jan Rehwinkel: None declared, Marie-Louise Frémond: None declared, Mary K. Crow Consultant of: AstraZeneca, Bristol Meyers Squibb, Lilly, Shannon Pharmaceuticals, Grant/research support from: Gilead, Lars Ronnblom Consultant of: AstraZeneca, Edward Vital Speakers bureau: GSK, Consultant of: AURINIA, SANDOZ, GSK, AstraZeneca, Roche, Modus, Grant/research support from: AstraZeneca, Marjan Versnel: None declared