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Objective: This study aimed to develop nomogram predicting overall survival (OS) of patients with peritoneal mesothelioma (PeM) using data from Surveillance, Epidemiology, and End Results (SEER) database and a Chinese institution. Methods: 1,177 PeM patients from the SEER database were randomized into training and internal validation cohorts at a 7:3 ratio. An external validation cohort consisting of 109 patients was enrolled from a Chinese institution. Nomogram was constructed based on variables identified through multivariate Cox regression analysis and evaluated by consistency indices (C-index), calibration plots, and receiver operating characteristic (ROC) curves. Patients were stratified into different risk categories, and Kaplan-Meier survival analysis was used to assess OS differences among these groups. Results: The nomogram, incorporating age, gender, histological type, T stage, M stage, and surgical status, demonstrated strong predictive capability with C-index values of 0.669 for the training cohort, 0.668 for the internal validation cohort, and 0.646 for the external validation cohort. The nomogram effectively stratified patients into high-risk and low-risk groups, with the high-risk group exhibiting significantly poorer OS (P < 0.05). Multivariate analysis confirmed gender, age, surgical intervention, and M stage as independent prognostic factors (P < 0.05). Specifically, male gender, older age, and unspecified M stage were linked to worse outcomes, while surgical intervention was associated with improved survival. Conclusion: The nomogram provide a reliable tool for predicting the survival in PeM patients, facilitating more informed treatment decisions. Key independent prognostic factors include gender, age, surgical intervention, and M stage. [ABSTRACT FROM AUTHOR]

Malignant peritoneal mesothelioma (MPM) is a rare tumor associated with a poor prognosis and a lack of consensus regarding treatment strategies. While the Checkmate 743 trial demonstrated the superiority of first-line nivolumab and ipilimumab over chemotherapy in malignant pleural mesothelioma (MPlM), few studies have assessed the effectiveness of immunotherapy against MPM, due to its rarity. Here, we report a major and sustained 12-month response in a 74-yearold female patient who received the anti-PD-1 nivolumab and the anti-CTLA4 ipilimumab as first-line therapy for diffuse MPM. PD-L1 was expressed and BAP1 expression was lost, as shown by immunohistochemistry, however the BAP1 gene was not mutated. Our findings suggest a role for ICI in non-resectable diffuse MPM exhibiting PD-L1 overexpression and loss of BAP1 expression, and instill new hope in their treatment. To our knowledge, this is the second reported case of dual immunotherapy used as first-line in MPM with a major clinical response. To investigate the clinical outcome, we conducted additional molecular analyses of the MPM tumor and we reviewed the literature on immunotherapy in MPM to discuss the role of PD-L1 and BAP1. [ABSTRACT FROM AUTHOR]

Malignant peritoneal and pleural mesothelioma are rare in young patients, with a paucity of data regarding clinical characteristics and outcomes. We aimed to describe the clinical characteristics, treatment strategies, and outcomes for pediatric and adolescent/young adult (AYA) patients. The National Cancer Database (NCDB) was queried for malignant peritoneal and pleural mesothelioma in pediatric and AYA patients (ages 0–39) from 2004 to 2019. Stratification was performed for pediatric (age 0–21) and young adult (age 22–39) patients. Chi-squared, multivariable cox regression, and Kaplan–Meier analyses were performed. We identified 570 total patients, 46 pediatric and 524 young adult, with mesothelioma (363 peritoneal and 207 pleural). There were significant differences in sex distribution as patients with peritoneal mesothelioma were more frequently female (63.1%). Patients with peritoneal mesothelioma were more likely to have radical surgery compared to pleural mesothelioma (56.7% v. 24.6%, respectively). A majority of patients with peritoneal and pleural mesothelioma received chemotherapy (66.4% and 61.4%, respectively). For peritoneal mesothelioma, surgical resection was associated with improved overall survival, whereas male sex, neoadjuvant chemotherapy, and radiation were associated with worse overall survival. For pleural mesothelioma, intraoperative chemotherapy was associated with improved overall survival, whereas Black race was associated with worse overall survival. Mean overall survival was greater for patients with peritoneal mesothelioma (125 months) compared to those with pleural mesothelioma (69 months), which remained significant after stratification of pediatric and young adult patients. By analyzing a large cohort of pediatric and AYA mesothelioma, this study highlights clinical, prognostic, and survival differences between peritoneal and pleural disease. Level III. Retrospective [ABSTRACT FROM AUTHOR]

Benign multicystic peritoneal mesothelioma (BMPM) is a rare condition, in which patients have multiple cystic lesions of the peritoneum. BMPM can mimic mucinous carcinomatosis and can thus create a diagnostic dilemma. We present the case of a 76-year-old woman who was referred for management of ascending colon adenocarcinoma and was noted to have several nonspecific cystic lesions in the abdomen and pelvis on preoperative computed tomography and diagnostic laparoscopy. Frozen section analysis suggested the lesions contained 'mucin'. Due to concern for metastases, right colectomy was aborted. Final histologic analysis of the laparoscopic biopsies revealed mesothelial cysts, consistent with BMPM, unrelated to her colon adenocarcinoma. Laparoscopic right colectomy was performed 2 weeks later. BMPM can create diagnostic and therapeutic uncertainty in patients with known visceral malignancies when discovered incidentally. Frozen section analysis may not be accurate in differentiating the two, and final histologic confirmation should be sought prior to definitive treatment. [ABSTRACT FROM AUTHOR]

Malignant peritoneal mesothelioma is an extremely rare and poorly recognized neoplasm in children. A 5-year-old boy presented with a 1-year history of progressive painless abdominal distension. A CT revealed a 19 × 19 × 11 cm3 cystic mass in the right hemiabdomen, without infiltrating the surrounding structures. The tumor was completely removed by surgery. The microscopic and immunohistochemical analyses confirmed peritoneal mesothelioma. Comprehensive genomic profiling revealed no major driving mutations including BAP1 , no fusions, but with amplifications of AURKA, AURKC, HLA-1B, ZNF-217, OR5F1 and MEN1 genes. Imaging follow-up 3 months after surgery revealed metastatic disease. The patient died of pneumonia at another hospital shortly after the last follow-up examination at our institution. Pediatric peritoneal mesothelioma is an extremely rare malignancy with limited targeted options and a poor prognosis. Some of the identified molecular genomic biomarkers require further exploration and validation in this cancer. [ABSTRACT FROM AUTHOR]

Malignant peritoneal mesothelioma (MPM) is a rare tumor associated with a poor prognosis and a lack of consensus regarding treatment strategies. While the Checkmate 743 trial demonstrated the superiority of first-line nivolumab and ipilimumab over chemotherapy in malignant pleural mesothelioma (MPlM), few studies have assessed the effectiveness of immunotherapy against MPM, due to its rarity. Here, we report a major and sustained 12-month response in a 74-year-old female patient who received the anti-PD-1 nivolumab and the anti-CTLA4 ipilimumab as first-line therapy for diffuse MPM. PD-L1 was expressed and BAP1 expression was lost, as shown by immunohistochemistry, however the BAP1 gene was not mutated. Our findings suggest a role for ICI in non-resectable diffuse MPM exhibiting PD-L1 overexpression and loss of BAP1 expression, and instill new hope in their treatment. To our knowledge, this is the second reported case of dual immunotherapy used as first-line in MPM with a major clinical response. To investigate the clinical outcome, we conducted additional molecular analyses of the MPM tumor and we reviewed the literature on immunotherapy in MPM to discuss the role of PD-L1 and BAP1.

Background The association between asbestos exposure and ovarian cancer has been questioned given the possible misdiagnosis of peritoneal mesothelioma as ovarian cancer. Aims To update a systematic review on ovarian cancer risk in women occupationally exposed to asbestos, exploring the association with the time since first exposure and the duration of exposure. Methods We searched PubMed from 2008 onwards, screened previous systematic reviews, combined standardized mortality ratios (SMR) using random effect models and quantified heterogeneity using the I 2 statistic. To assess tumour misclassification, we compared the distribution of observed excess ovarian cancers (OEOC) to that expected (EEOC) from the distribution of peritoneal cancers in strata of latency and exposure duration. Results Eighteen publications (20 populations), including a pooled analysis of 21 cohorts, were included. The pooled SMR was 1.79 (95% confidence interval 1.38–2.31), with moderate heterogeneity between studies (I 2 = 42%), based on 144 ovarian cancer deaths/cases. The risk was increased for women with indirect indicators of higher exposure, longer duration and latency, and lower for chrysotile than for crocidolite exposure. The effect of duration and latency could not be completely disentangled, since no multivariate analysis was available for time-related variables. The dissimilarity index between OEOC and EEOC for the time since first exposure was small suggesting a similar pattern of risk. Conclusions While some misclassification between ovarian and peritoneal cancers cannot be excluded, the observed excess risk of ovarian cancer should be added to the overall disease burden of asbestos. [ABSTRACT FROM AUTHOR]

IntroductionMalignant peritoneal mesothelioma (MPM) is an extremely rare tumor with nonspecific clinical manifestations, making diagnosis challenging.Case presentationHerein, we report a case of MPM with occult onset presenting with bilateral hydronephrosis and renal insufficiency. A 30-year-old man was admitted to the Urology Department because of recurrent bilateral lower back pain. The etiology was unclear after a series of laboratory tests, imaging examinations, bone marrow aspiration, renal puncture biopsy, ascites examination, ureteroscopy, and so on. Finally, MPM was diagnosed by laparoscopic exploration and biopsy. Moreover, during the course of the disease, the patient's bilateral ureters were compressed, and the obstruction could not be relieved after the placement of ordinary ureteral stents. Percutaneous nephrostomy or metal ureteral stenosis was appropriate in managing malignant ureteral obstruction as it could improve renal function.ConclusionsThe onset of this case was insidious, and the diagnosis was difficult, with a poor prognosis. To date, only a handful of cases have been reported. We hope this case can provide some enlightenment for our clinical work.

Mesotheliomas are aggressive malignant tumors which can occur most commonly in the pleural space, however can occur in the peritoneum in those with an extensive history of asbestos exposure. Primary peritoneal mesothelioma is relatively rare and is a fatal diagnosis. The prognosis of primary peritoneal mesothelioma is very poor and individuals are at high risk of developing mesothelioma in another cavity within the first year after initial diagnosis. Herein, we present a case of primary peritoneal mesothelioma, presenting as small bowel obstruction.

Abstract Peritoneal malignancies represent a diagnostic challenge for abdominal radiologists, oncologists, surgeons and pathologists in multidisciplinary teams, who must address their differential diagnosis, staging and treatment. In this article, we explain the pathophysiology of these processes and lay out the role of different imaging techniques in their evaluation. Then, we review the clinical and epidemiological aspects, the main radiological features and the therapeutic approaches for each primary and secondary peritoneal neoplasm, with surgical and pathological correlation. We further describe other rare peritoneal tumors of uncertain origin and a variety of entities that may mimic peritoneal malignancy. Finally, we summarize the key imaging findings of each peritoneal neoplasm to facilitate an accurate differential diagnosis that may impact patient management. Clinical relevance statement Imaging plays an essential role in the evaluation of peritoneal malignancies, assessing their extension, detecting unfavorable sites of involvement and facilitating an accurate differential diagnosis, helping to choose the best therapeutic approach. Graphical abstract

Benign Multicystic Peritoneal Mesothelioma (BMPM) is an exceedingly rare benign abdominal neoplasm with fewer than 200 cases reported worldwide. Owing to its rarity, vague clinical picture, and elusive causes, diagnosis is often delayed or missed. Histopathological examination and immunohistochemical staining are crucial for definitive diagnosis. However, due to lack of substantial literature, the standard of care and future prognosis remain subjects of inquiry. We present a case report of one female patient diagnosed with BMPM and treated with surgical resection. [ABSTRACT FROM AUTHOR]

Peritoneal malignancies represent a diagnostic challenge for abdominal radiologists, oncologists, surgeons and pathologists in multidisciplinary teams, who must address their differential diagnosis, staging and treatment. In this article, we explain the pathophysiology of these processes and lay out the role of different imaging techniques in their evaluation. Then, we review the clinical and epidemiological aspects, the main radiological features and the therapeutic approaches for each primary and secondary peritoneal neoplasm, with surgical and pathological correlation. We further describe other rare peritoneal tumors of uncertain origin and a variety of entities that may mimic peritoneal malignancy. Finally, we summarize the key imaging findings of each peritoneal neoplasm to facilitate an accurate differential diagnosis that may impact patient management. Clinical relevance statement Imaging plays an essential role in the evaluation of peritoneal malignancies, assessing their extension, detecting unfavorable sites of involvement and facilitating an accurate differential diagnosis, helping to choose the best therapeutic approach. Key points: The most frequent peritoneal malignancy is peritoneal carcinomatosis of ovarian or gastrointestinal origin. Primary peritoneal serous carcinoma mimics ovarian carcinomatosis but with no adnexal mass. Loculated ascites with scalloping should raise suspicion of pseudomyxoma peritonei originating from a ruptured appendiceal mucinous neoplasm. Peritoneal sarcomatosis usually presents as heterogeneous bulky masses and hypervascular spherical implants, with minimal ascites and no lymphadenopathies. Peritoneal lymphomatosis may show homogeneous bulky masses, lymphadenopathies, small bowel wall thickening and hepatosplenomegaly. [ABSTRACT FROM AUTHOR]

Background/Aim: Mesotheliomas are tumors similar to, and probably derived from, mesothelial cells. They carry acquired chromosomal rearrangements, deletions affecting CDKN2A, pathogenetic polymorphisms in NF2, and fusion genes which often contain the promiscuous EWSR1, FUS, and ALK as partner genes. Here, we report the cytogenomic results on two peritoneal mesotheliomas. Materials and Methods: Both tumors were examined using G-banding with karyotyping and array comparative genomic hybridization (aCGH). One of them was further investigated with RNA sequencing, reverse transcription polymerase chain reaction (RT-PCR), Sanger sequencing, and fluorescence in situ hybridization (FISH). Results: In the first mesothelioma, the karyotype was 25~26,X,+5,+7,+20[cp4]/50~52,idemx2[cp7]/46,XX[2]. aCGH detected gains of chromosomes 5, 7, and 20 with retained heterozygosity on these chromosomes. In the second tumor, the karyotype was 46,XX,inv(10)(p11q25)[7]/46,XX[3]. aCGH did not detect any gains or losses and showed heterozygosity for all chromosomes. RNA sequencing, RT-PCR/Sanger sequencing, and FISH showed that the inv(10) fused MAP3K8 from 10p11 with ABLIM1 from 10q25. The MAP3K8::ABLIM1 chimera lacked exon 9 of MAP3K8. Conclusion: Our data, together with information on previously described mesotheliomas, illustrate two pathogenetic mechanisms in peritoneal mesothelioma: One pathway is characterized by hyperhaploidy, but with retained disomies for chromosomes 5, 7, and 20; this may be particularly prevalent in biphasic mesotheliomas. The second pathway is characterized by rearrangements of MAP3K8 from which exon 9 of MAP3K8 is lost. The absence of exon 9 from oncogenetically rearranged MAP3K8 is a common theme in thyroid carcinoma, lung cancer, and spitzoid as well as other melanoma subtypes. [ABSTRACT FROM AUTHOR]

Diffuse malignant peritoneal mesothelioma (DMPM) prognosis was improved by the locoregional treatment combining cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC). HIPEC is a multiparametric treatment with multiple protocols proposed and reviewed in this work. A systematic review of medical literature was performed according to PRISMA guidelines. The search strategy used "malignant peritoneal mesothelioma" and "HIPEC" as keywords in three databases. Studies were included if reporting precisely the HIPEC regimen and the related outcomes, if comparing regimen, or if reporting national/international guidelines. The GRADE methodology was used to rate the level of evidence. Twenty-eight studies were included in this review: 1 was a meta-analysis, 18 reported cohort outcomes, 4 retrospectively compared HIPEC regimens, and 5 were guidelines. Six HIPEC regimens were found, 4 with one drug (cisplatin, mitomycine-C, carboplatin, oxaliplatin), 2 using two drugs (cisplatin-doxorubicin or cisplatin-mitomycine-C). Cisplatin, up to 250 mg/m2 over 90 min, appeared as the key HIPEC drug with a toxicity profile well controlled by the concomitant intravenous perfusion of sodium thiosulfate. Comparative studies tended to show that a bi-drug regimen led to better long-term oncologic outcomes, with cisplatin 50 mg/m2 plus doxorubicin 15 mg/m2 being safe and more efficient. This late protocol was the most widely used and recommended in 3 out of 4 international guidelines. Cisplatin was the preferred drug for HIPEC in DMPM patients. Most of the time, it was combined with doxorubicin for 90 min. A harmonization of protocols and further comparative studies are needed to optimize HIPEC regimen choice. [ABSTRACT FROM AUTHOR]

Extrapelvic endometriosis is a rare presentation of endometriosis with atypical clinical symptoms. It can mimic peritoneal surface malignancy, as well as some abdominal infectious diseases. A 29-year-old Moroccan woman presented with abdominal pain, progressive abdominal distention, and an intermittent inflammatory syndrome. Imaging revealed multiple, progressively growing abdominal cysts. She had elevated tumor markers CA125 and CA19.9. Despite thorough investigation, several differential diagnoses persisted for a long time. Definitive pathological diagnosis could only be established after debulking surgery. Literature review on malignant and benign conditions causing multicystic abdominal distention is provided. When definitive diagnosis is not established, but suspicion for peritoneal malignancy remains, a debulking procedure can be undertaken. Organ preservation can be pursued whenever benign disease is still considered. In case of malignancy, short-term (curative) debulking procedure with or without hyperthermic intraperitoneal chemotherapy (HIPEC) can be proposed. [ABSTRACT FROM AUTHOR]

Malignant mesotheliomas most often affect the pleura and tend to spread locally within the originating cavity. Mesotheliomas are already rare diseases, and cases with synchronous pleural and peritoneal involvement are scarce in the literature. Mesothelioma in children is a rare disease representing only 0.9% of all mesotheliomas. They exhibit similar distribution and characteristics as mesotheliomas in adults and generally, a poor prognosis. Due to the rarity, there is no standardized treatment recommendation for children with mesothelioma. Though the malignant mesothelioma tends to spread locally within the originating cavity, pleuM have been reported to metastasize into the peritoneal cavity and vice versa. As there are only few studies concerning the metastatic spread of mesothelioma, it is difficult to define a precise incidence and risk factors for patients to develop metastases of the other mesothelium. There is no standardized therapeutic recommendation for patients with synchronous pleuM and perM. Our patient proved to profit from a radical two-stage surgical approach in combination with locoregional chemotherapy; she showed no sign of tumor recurrences 9 years after tumor resection. In conclusion, clinical studies are needed to confirm the benefit of this treatment and to determine its limitations and selection criteria. [ABSTRACT FROM AUTHOR]

Diffuse malignant peritoneal mesothelioma (PM) is a rare neoplasm, traditionally associated with a poor prognosis. There are other varieties of PM that are even less frequent and of uncertain malignancy. Cytoreductive surgery (CRS) with hyperthermic intraperitoneal chemotherapy (HIPEC) has achieved prolonged survival in selected patients. The aim of this study is to analyze the patients with PM assessed in our center. Clinicopathological characteristics, diagnostic procedures and survival results from patients with PM appraised at our unit, according to the applied treatment, were analyzed. Seventeen patients were assessed between 2007 and 2019. Three cases had multicystic PM that were treated with complete CRS + HIPEC; all patients are alive and free of disease after a long follow-up. Three other cases had biphasic PM; a curative treatment could be performed in none of them, and their survival was minimal (<6 moths). Lastly, 11 cases with epithelioid PM were treated. Two cases were considered unresectable at laparoscopy (PCI 39); one of them had a long survival (67 months) with three iterative laparoscopic palliatives HIPECs for refractory ascites. The other nine cases were treated with curative CRS + HIPEC, with a median PCI of 14 (range 4–25), and a median overall survival (OS) of 58 months, with a 5-year OS of 47.4%. In conclusion, CRS + HIPEC, when possible, appears to be the optimal treatment for patients with PM. Knowledge of this therapeutic option is crucial, both to offer it to patients and to avoid delays in their referral to appropriate centers for treatment. [ABSTRACT FROM AUTHOR]

Malignant peritoneal mesothelioma (MPM) is a rare malignancy, presenting with non‐specific and potentially‐misleading manifestations. It represents a diagnostic pitfall as it mimics ovarian carcinoma. Maintaining a low diagnostic threshold, obtaining a detailed history, and utilizing immunohistochemical markers to diagnose MPM is crucial as early diagnosis and treatment might improve survival. We report a case of multiple primary malignancies involving malignant peritoneal mesothelioma in a 55‐year‐old female with a remote history of radiotherapy for thyroid papillary adenocarcinoma. Her advanced disease made her unfit for chemotherapy and debulking surgery. She died of cardiac arrest 2 days after palliative care referral. [ABSTRACT FROM AUTHOR]

Peritoneal mesothelioma is a rare neoplasm that is associated with multiple diagnostic and therapeutic challenges. Therapeutic guidelines are scarce and based on extrapolative data. Histopathological diagnosis is difficult as neither the morphological finding nor the immunohistochemical stains are specific. The mainstay treatment for resectable disease is cytoreductive surgery with intraperitoneal chemotherapy being a valuable addition. Treatment of non-resectable cases includes platinum-based chemotherapy, immune checkpoint inhibitors, and bevacizumab. We present a case of a 49-year-old woman suffering from inoperable peritoneal mesothelioma, which was initially diagnosed as ovarian cancer and treated accordingly. [ABSTRACT FROM AUTHOR]

Biomarker testing has increasingly been adopted in oncology for diagnostic, prognostic, and predictive purposes. Several tumor types undergo reflexive biomarker testing, including immunohistochemistry and next generation sequencing (NGS), to screen for hereditary tumor predisposition syndromes and identify optimal treatment regimens. Routine clinical biomarker testing, however, does not identify less common hereditary cancer syndromes, which instead requires comprehensive genomic profiling (CGP). This report describes the case of a patient with occupational exposure to asbestos who developed peritoneal mesothelioma and experienced a dramatic response to platinum-based chemotherapy. Shortly thereafter, he was diagnosed with metastatic sinonasal melanoma. The uncommon co-occurrence of these two primary malignancies prompted analysis of the patient’s mesothelioma by CGP, which identified a pathogenic BAP1 splice site mutation (c.438-1G > A, NM_004656.4, 71 % allele frequency). The melanoma was subsequently evaluated using a clinical NGS panel and found to harbor the same mutation (84 % allele frequency), strongly suggesting that the pathogenic variant is present in the patient’s germline (diagnostic of BAP1 tumor predisposition syndrome). These results enabled recommendation of germline testing and suggestion of active clinical trials of targeted therapy to the treating physician, highlighting the important role of CGP in the delivery of precision medicine.

Abstract Malignant peritoneal mesothelioma (MPM) is a rare malignancy, presenting with non‐specific and potentially‐misleading manifestations. It represents a diagnostic pitfall as it mimics ovarian carcinoma. Maintaining a low diagnostic threshold, obtaining a detailed history, and utilizing immunohistochemical markers to diagnose MPM is crucial as early diagnosis and treatment might improve survival.

Peritoneal tissue is the second most affected site by malignant mesothelioma linked to asbestos exposure. This scoping review aims to summarize the findings of the studies in which asbestos fibers in the peritoneum were quantified by electron microscopy, occasionally associated with spectroscopy, both in neoplastic and non-neoplastic tissue. The 9 studies selected comprised 62 cases, out of whom 100 samples were analyzed. Asbestos fibers were detected in 58 samples (58%). In addition, 28 cases had diagnosis of peritoneal mesothelioma. For 32 cases, a lung tumor sample was available: 28/32 samples analyzed presented asbestos fibers; 18/32 reported amphiboles with a range from not detected to 14.2 million fibers per gram of dry tissue (mfgdt); 18/32 reported chrysotile, with a range of 0 to 90 mfgdt. The studies were heterogeneous for type of samples, analytical technology, and circumstances of exposure to asbestos. To evaluate asbestos fibers in the peritoneum and to better understand the association between asbestos exposure and malignant peritoneal mesothelioma, it is desirable that the search for asbestos fibers becomes a routine process every time peritoneal tissue is accessible. [ABSTRACT FROM AUTHOR]

In malignant mesotheliomas, cases involving the peritoneum as the primary site are rare, accounting for approximately 10% of all mesothelioma cases. We report a case of medical-type peritoneal mesothelioma leading to death 2 months after the onset of fever of unknown origin, along with a review of the literature. A 76-year-old man presented with a fever of unknown origin over 4 weeks. Thoracoabdominal computed tomography (CT) scan showed increased mesenteric adipose tissue density. 18F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) scan showed diffuse hyperaccumulation in the mesentery and hyperaccumulation in the intraperitoneal and parasternal lymph nodes. A thoracoscopic biopsy of the parasternal lymph nodes revealed metastatic peritoneal mesothelioma. The treatment plan was discussed with him and his family, and the best supportive care was provided. 2 months later, he died from multiple organ failure. Underlying malignant tumors cause 38% of mesenteric panniculitis cases. Symptoms accompanied by lymphadenopathy within the area of mesenteric panniculitis are highly suggestive of malignancy. Peritoneal mesothelioma can be classified as (1) classical, which is accompanied by abdominal pain, ascites, and abdominal masses; (2) surgical, which is accompanied by hernia incarceration and intestinal occlusion; and (3) medical, wherein systemic symptoms, such as fever and weight loss, are primarily observed. The medical-type peritoneal mesothelioma, wherein systemic symptoms are primarily observed, has a poorer prognosis than the other types. FDG-PET/CT is an effective diagnostic modality for peritoneal mesothelioma and typically shows diffuse hyperaccumulation along the peritoneal surface.

Background: Malignant peritoneal mesotheliomas (MPMs) are rare tumors with overlapping clinical and histopathological features, especially with epithelial ovarian carcinomas (EOCs). There is no substantial documentation on these rare tumors from our country.Objective: To study the clinicopathological features including immunohistochemical (IHC) profile and clinical outcomes of 14 MPMs, diagnosed at our institution.Materials and Methods: This was a retrospective study, wherein 14 cases of MPM, occurring in female patients, diagnosed at our institution, between January 2008 and May 2019 were included, after a critical review.Results: Median age was 54.5 years. Most patients presented with ascites, omental nodularity, and fat stranding. Microscopically, most cases (11, 78.6%) displayed epithelioid morphology, followed by biphasic pattern (2, 14.3%) and a single case of well-differentiated MPM. IHC, diagnostic sensitivity and specificity of calretinin were 100% (13/13) and 85.7%; of HBME1 were 100% (5/5) and 100%; and of podoplanin (D2-40) were 60% (2/5) and 100%. Other positively expressed immunomarkers were epithelial membrane antigen (n = 2/5, 40%), cytokeratin 5/6 (n = 4/4, 100%), and WT1 (n = 9/10, 90%). Most patients (5/12, 41.7%) were treated with chemotherapy. The 3-year disease-free and overall survival rates were 25.7% and 54%, respectively, including improved survival trend in patients with epithelioid type of MPMs.Conclusion: MPMs are diagnosed with a combination of clinicopathological features and optimal IHC markers. Their differentiation from EOCs and other metastatic carcinomas is imperative in view of significant treatment implications. [ABSTRACT FROM AUTHOR]

Background: Peritoneal surface malignancies (PSMs) are a heterogenous group of primary and metastatic cancers affecting the peritoneum. They are associated with poor long-term outcomes. Many centers around the world adopt cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) in routine clinical practice for these otherwise condemned patients despite a lack of high-level evidence from randomized control trials. This study aimed to investigate and present our 10-year experience with this controversial method, CRS and HIPEC, for PSM in a single tertiary center in a Baltic country. Methods: Patients who underwent CRS and HIPEC at Vilnius University Hospital Santaros Klinikos between 2011 and 2021 were included in this retrospective study. Overall survival was the primary study outcome. Secondary outcomes included postoperative morbidity and mortality, and local or systemic recurrence rates. Results: Sixty-nine patients who underwent CRS and HIPEC were included in the study. Most patients underwent treatment for peritoneal metastases from colorectal, ovarian, and appendiceal cancers. Six (8.7%) patients received CRS and HIPEC for primary peritoneal neoplasm—pseudomyxoma peritonei. The mean peritoneal carcinomatosis index score was 12 ± 7. Complete cytoreduction was achieved in 62 (89.9%) patients. The mean OS was 39 ± 29 months. The mean survival of patients with PSMs of different origin was as follows: 39 ± 25 (95% CI: 28–50) months for colorectal cancer, 44 ± 31 (95% CI: 30–58) months for ovarian cancer, 32 ± 21 (95% CI: 21–43) months for appendiceal cancer, 422 ± 1 (95% CI: 12–97) months for pseudomyxoma peritonei, and 7 months for gastric cancer. Conclusions: The current study demonstrated the results of the CRS and HIPEC program in a single Baltic country tertiary center. Patients who underwent CRS and HIPEC for PSMs achieved moderate survival rates with acceptable postoperative morbidity and mortality risk. [ABSTRACT FROM AUTHOR]

Localized mesothelioma is a rare disease with very few reports of presentation in visceral organs. We report a case of localized gastric mesothelioma with lymph node metastasis in a 32-year-old man without asbestos exposure. A failed attempt at resection was made before presentation at another center. He was given perioperative chemotherapy that was followed by a D2 radical subtotal gastrectomy and hyperthermic intraperitoneal chemotherapy. Histopathology showed epithelioid mesothelioma with nodal metastasis but without visceral peritoneal involvement. Cytoreductive surgery and regional chemotherapy are standard in diffuse mesothelioma. Management of localized mesothelioma is anecdotal; however aggressive surgery plays a central role with selective use of perioperative chemotherapy. [ABSTRACT FROM AUTHOR]

Introduction: Asbestos workers have a higher risk of developing mesothelioma; however, few studies have looked at specific jobs and job locations within asbestos factories. The purpose of this study was to investigate asbestos exposure in different job locations of the Tyler, Texas asbestos plant to determine if there was a relationship between the duration of exposure and air fiber concentration burden in workers who developed pleural versus peritoneal mesothelioma., Methods: This study used a patient information database to compile secondary data on 23 workers who died from mesothelioma through 2011. The airborne fiber exposure burdens for each of the 23 workers were estimated and then stratified by job location category and by type of mesothelioma for analysis., Results: Most of the worker cases were assigned to the forming area which had the overall highest fiber concentration of all the plant's job locations. Workers who developed pleural mesothelioma spent the most time in the packing and miscellaneous locations, whereas workers who developed peritoneal mesothelioma worked mostly in the forming and miscellaneous locations. There were significant differences in days worked and estimated airborne exposure fiber burden between the pleural and peritoneal mesothelioma cases in the forming and curing locations., Conclusion: Results from this study reiterate the association between occupational asbestos exposure and mesothelioma, emphasizing the importance of concentration of respirable asbestos dust levels and duration of exposure., (© 2024 Wiley Periodicals LLC.)

Cytoreductive surgery with HIPEC has definite application to the management of selected patients with peritoneal metastases. Patients who profit most have a complete cytoreductive surgery. Higher-grade tumors such as colorectal cancer, gastric cancer, and ovarian malignancy are benefited by CRS and HIPEC only under limited circumstances. High-grade tumor invades subperitoneal lymphatics where HIPEC is not effective. Options to traditional HIPEC for treatment of invasive intraabdominal malignancies with peritoneal metastases must be explored., (© 2024 Wiley Periodicals LLC.)

Objective: This study aimed to develop nomogram predicting overall survival (OS) of patients with peritoneal mesothelioma (PeM) using data from Surveillance, Epidemiology, and End Results (SEER) database and a Chinese institution., Methods: 1,177 PeM patients from the SEER database were randomized into training and internal validation cohorts at a 7:3 ratio. An external validation cohort consisting of 109 patients was enrolled from a Chinese institution. Nomogram was constructed based on variables identified through multivariate Cox regression analysis and evaluated by consistency indices (C-index), calibration plots, and receiver operating characteristic (ROC) curves. Patients were stratified into different risk categories, and Kaplan-Meier survival analysis was used to assess OS differences among these groups., Results: The nomogram, incorporating age, gender, histological type, T stage, M stage, and surgical status, demonstrated strong predictive capability with C-index values of 0.669 for the training cohort, 0.668 for the internal validation cohort, and 0.646 for the external validation cohort. The nomogram effectively stratified patients into high-risk and low-risk groups, with the high-risk group exhibiting significantly poorer OS (P < 0.05). Multivariate analysis confirmed gender, age, surgical intervention, and M stage as independent prognostic factors (P < 0.05). Specifically, male gender, older age, and unspecified M stage were linked to worse outcomes, while surgical intervention was associated with improved survival., Conclusion: The nomogram provide a reliable tool for predicting the survival in PeM patients, facilitating more informed treatment decisions. Key independent prognostic factors include gender, age, surgical intervention, and M stage., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Fang, Xiang, Jiang, Li, Yuan, Pei, Li and Sun.)

Abstract The peritoneal cavity is the second commonest site of mesothelioma after the pleural cavity. There are five histological types of peritoneal mesothelioma with variable symptomatology, clinical presentation and prognosis. Cystic mesothelioma is a borderline malignant neoplasm with a favourable prognosis, well-differentiated papillary mesothelioma is generally a low-grade malignancy, and all other varieties such as epithelioid, sarcomatoid and biphasic mesothelioma are highly malignant types of peritoneal mesothelioma with poor prognosis. Malignant peritoneal mesothelioma was considered inevitably fatal prior to the introduction of cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) in selected cases where long-term survival and cure could be achieved. However, the survival benefits following CRS and HIPEC mainly depend on completeness of cytoreduction, which come at the cost of high morbidity and potential mortality. Using the acronym ‘PAUSE’, we aimed at describing the key imaging findings that impact surgical decision-making in patients with peritoneal mesothelioma. PAUSE stands for peritoneal cancer index, ascites and abdominal wall disease, unfavourable sites of involvement, small bowel and mesenteric disease and extraperitoneal disease. Reporting components of ‘PAUSE’ is crucial for patient selection. Despite limitations of CT in accurately depicting the volume of disease, describing findings in terms of PAUSE plays an important role in excluding patients who might not benefit from CRS and HIPEC.

Well-differentiated papillary mesothelioma has been renamed well-differentiated papillary mesothelial tumour (WDPMT) in the current WHO classification because all mesotheliomas are now regarded as malignant. WDPMT is now defined as a non-invasive papillary mesothelial proliferation, with retained labelling for BAP1-desirable. The current WHO classification also includes mesothelioma in situ (MIS), which is defined as pre-invasive flat or papillary proliferation of mesothelial cells with a loss of BAP1 or MTAP. WDPMT has been variably defined in the past but was thought to occur more commonly in women and pursue a more indolent course than mesothelioma, but its progression to invasive disease has occasionally been reported. Here, we report a case of a 68-year-old woman with a history of asbestos exposure and an underlying diagnosis of Ehlers Danlos syndrome who was diagnosed with symptomatic WDPMT of the peritoneum that progressed to mesothelioma within two years. On retrospective analysis, the WDPMT showed a loss of BAP1. We suggest that a loss of BAP1 in WDPMT should be reported, since these lesions may show aggressive behaviour, and that they may best be regarded as similar to mesothelioma in situ.

Abstract Introduction Diffuse malignant peritoneal mesothelioma (DMPM) is a rare malignant neoplasm with poor survival that shares some similarities with the best-known pleural variant, pleural mesothelioma. The recent European Reference Network on Rare Adult Cancers (EURACAN)/International Association for the Study of Lung Cancer (IASLC) proposals attempted to improve the histological diagnosis and patient risk stratification. Herein, we investigated whether the pathology recommendations and suggestions of the pleural proposals were applicable to diffuse malignant peritoneal mesothelioma. Methods Fifty multiple laparoscopic biopsies of DMPM were consecutively collected at the Pathology Unit of the University of Bari. A two-tier system, i.e., low, and high grade, was used to categorize 34 epithelioid DMPMs. Architectural patterns, cytological features and stromal changes were also reported. Immunohistochemistry was performed for BRCA1-associated protein 1 (BAP1), programmed death-ligand 1 (PD-L1), and Ki67, while fluorescence in situ hybridization (FISH) was performed for p16/cyclin-dependent kinase inhibitor 2A (CDKN2A). Results High-grade epithelioid mesothelioma, high Ki67, and p16/CDKN2A deletion were significantly associated with short survival (p = 0.004, p

• Harmonizing imaging practices will allow for well-informed decisions in oncology. • Imaging technology impacts surgical approaches and will shape future treatments. • 4D MRI can assess diaphragm function in the presence of malignant pleural effusion. • AI may predict outcome and aid treatment selection to improve precision oncology. • Perfusion MRI will benefit from automated reporting for early contrast enhancement. • Dedicated evaluation criteria for peritoneal metastases will aid drug development. Imaging continues to gain a greater role in the assessment and clinical management of patients with mesothelioma. This communication summarizes the oral presentations from the imaging session at the 2023 International Conference of the International Mesothelioma Interest Group (iMig), which was held in Lille, France from June 26 to 28, 2023. Topics at this session included an overview of best practices for clinical imaging of mesothelioma as reported by an iMig consensus panel, emerging imaging techniques for surgical planning, radiologic assessment of malignant pleural effusion, a radiomics-based transfer learning model to predict patient response to treatment, automated assessment of early contrast enhancement, and tumor thickness for response assessment in peritoneal mesothelioma. [ABSTRACT FROM AUTHOR]

Malignant peritoneal mesothelioma is a rare malignancy arising from the serosa of the peritoneal cavity. It is diagnosed based on suspicious findings on cross sectional imaging and a tissue biopsy showing confirmatory histologic and immunohistochemical features. The disease is hallmarked by its propensity to progress mainly in the peritoneal cavity. In selected patients, surgical cytoreduction and hyperthermic intra-operative peritoneal chemotherapy has become the initial preferred treatment and is associated with provide prolonged in many patients. Systemic chemotherapy using a couplet of cisplatin or gemcitabine with pemetrexed has modest response rates and duration of response. Expression of PD-L1 has been demonstrated in peritoneal mesothelioma tumors and there has been significant interest in the use of check point blockade targeted against PD-L1 in this clinical setting. Future clinical research using a combination of check point blockade with surgical cytoreduction is a high clinical priority. [ABSTRACT FROM AUTHOR]

Mesothelioma is a rare malignant neoplasm with poor survival. It mainly affects the pleura (90%) but can arise in all serous cavities: peritoneum (5-10%), pericardium and tunica vaginalis testis (<1%). The onset of pleural mesothelioma is strictly related to asbestos exposure with a long latency time. The causal link with asbestos has also been suggested for peritoneal mesothelioma, while the importance of exposure in the onset of pericardial and tunica vaginalis testis mesotheliomas is not well known. Mesothelioma remains an aggressive and fatal disease with a five-year mortality rate higher than 95%. However, new therapeutic approaches based on molecular-targeted and immunomodulatory therapies are being explored but have conflicting results. In this context, the identification of critical targets appears mandatory. Awareness of the molecular and physiological changes leading to the neoplastic degeneration of mesothelial cells and the identification of gene mutations, epigenetic alterations, gene expression profiles and altered pathways could be helpful for selecting targetable mechanisms and molecules. In this review, we aimed to report recent research in the last 20 years focusing on the molecular pathways and prognostic factors in peritoneal mesothelioma and their possible diagnostic and therapeutic implications. [ABSTRACT FROM AUTHOR]

Mesothelioma is a rare malignant neoplasm with poor survival. It mainly affects the pleura (90%) but can arise in all serous cavities: peritoneum (5-10%), pericardium and tunica vaginalis testis (

Abstract Background Peritoneal mesothelioma is a rare abdominal disease; that occasionally occurs congenitally in younger calves. Cytologic examination of peritoneal effusion (PE) was utilized to diagnose this disease, and was not diagnostic. Diagnostic accuracy has been elevated by recent use of ultrasonography (US), despite most diagnoses have been obtained post-mortem in slaughter houses or during clinical necropsy. In humans, ante-mortem diagnosis is highly associated with clinical use of computed tomography (CT) and laparoscopy together with imaging-assisted biopsy. The present report evaluates the diagnostic applicability of CT and laparoscopy as well as US via the practical application of these imaging modalities in an affected calf, and compares the cytologic and histologic findings among in PE, and specimens obtained from fine-needle aspiration and core-needle biopsy. In addition, the present results were reviewed in comparison with those of previous bovine and human reports. Case presentation A 58-day-old male Japanese black calf presented first with scrotal swelling, followed by progressive abdominal distention. Abnormalities of the case included: 1) accumulation of anechoic PE inside the swollen scrotum and abdomen; 2) formation of multiple echogenic nodules within the peritoneal membrane based on US images; 3) presence of hyper-dense spots (suspected calcification) along the margins of the nodules; 4) anatomic connections between intra-abdominal nodular lesions and the swollen tunica vaginalis via the inguinal region based on CT images; 5) serosanguineous-colored and less-turbid characteristics of PE; and 6) formation of multiple nodules over all of the serosa of the rumen as well as the peritoneal wall based on laparoscopic views. Fine-needle aspiration and core-needle biopsy were successfully performed under US and laparoscopic observations, respectively. Histology findings of the core-needle biopsy specimen appeared more indicative (characterization of tubular structures comprised of cubical or columnar abnormal mesothelial cell linings) diagnostically of peritoneal mesothelioma than did findings of the fine-needle aspiration specimen. Conclusions To the best of our knowledge, this report is the first description of clinical applications of CT and laparoscopy to diagnose peritoneal mesothelioma in a calf. Laparoscopy enhanced the diagnostic accuracy due to clear gross visualization of the intra-abdominal abnormalities and applicability to imaging-guided core-needle biopsy.

Malignant mesothelioma is a rare disease that typically occurs in older patients with prolonged exposure to asbestos. The majority of mesothelioma occurs in the pleura. Less frequently, patients will develop peritoneal mesothelioma without pleural involvement. Within this subset of patients, therapeutically targetable somatic mutations are being identified. Here we describe a 17-year old female with metastatic peritoneal mesothelioma without prior asbestos history. After disease progression on cytotoxic chemotherapy, the small molecule crizotinib, an Anaplastic Lymphoma Kinase (ALK) inhibitor, was administered based on detection of somatic STRN-ALK fusion mutation. Rapid symptomatic improvement and tumor response was followed by surgical eradication of disease. The patient remains disease-free over 12 months later. This case is an example of a rare subset of young females who may develop peritoneal mesothelioma, without pleural involvement, secondary to ALK translocations. This report demonstrates the growing knowledge of this rare subgroup and the need for further investigation into ALK translocation as a driver for peritoneal mesothelioma development, progression, and evaluation of ALK inhibitors in malignant mesothelioma.

Here, we present a unique case involving a female patient in her 40s with synchronous malignant pleural and peritoneal mesothelioma, despite lacking a history of asbestos exposure. The patient's initial symptoms included dyspnoea, chest pain, cough, fever, appetite loss, and weight loss over a month. Clinical evaluation led to the identification of right-sided pleural effusion, prompting consideration of differential diagnoses, such as tubercular or malignant pleural effusion. A thoracoscopy-guided biopsy, followed by histopathological examination and immunohistochemical staining, confirmed the diagnosis of mesothelioma. Chemotherapy was initiated as part of the treatment plan. The prognosis for this condition is generally bad; however, unusual cases of extended survival have been documented. The complexities of our case underscore the critical necessity for a thorough and aggressive evaluation of pleural effusion cases to unveil rare underlying causes, such as mesothelioma., Competing Interests: Human subjects: Consent was obtained or waived by all participants in this study. Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work., (Copyright © 2024, Reddy et al.)

Background: Multicystic mesothelial cyst is a rare, and usually benign, tumor which is rarely diagnosed preoperatively due to the poor specificity of its symptomatology., Methods: We report the case of a 63-year-old man with multiple comorbidities (e.g. cryptogenic cirrhosis, chronic heart failure) and a history of surgical resection of a giant abdominal cyst, who complained of recurrent intermittent abdominal pain and vomiting that appeared several weeks before. Abdominal computed tomodensitometry (CT) revealed multiple diffusely localized cysts in the abdominal cavity, ranging from 30 mm to 210 mm., Results: The patient underwent surgical resection of twelve intra-abdominal cysts, identified at final pathology as benign mesothelial cysts, which were probably a recurrence following the previous surgery for a single intra-abdominal cyst. Three months later, the patient recurred with development of two new intraperitoneal cysts, with an increasing volume on CT at last follow-up (18 months). Surveillance was recommended given the patient's comorbidities and the absence of symptoms., Conclusions: Surgical resection is the treatment of choice for multicystic peritoneal mesothelioma, a rare disease that should be considered more as a borderline tumor than a benign tumor, given the high risk of recurrence and possible malignant transformation.

The peritoneal cavity is the second commonest site of mesothelioma after the pleural cavity. There are five histological types of peritoneal mesothelioma with variable symptomatology, clinical presentation and prognosis. Cystic mesothelioma is a borderline malignant neoplasm with a favourable prognosis, well-differentiated papillary mesothelioma is generally a low-grade malignancy, and all other varieties such as epithelioid, sarcomatoid and biphasic mesothelioma are highly malignant types of peritoneal mesothelioma with poor prognosis. Malignant peritoneal mesothelioma was considered inevitably fatal prior to the introduction of cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) in selected cases where long-term survival and cure could be achieved. However, the survival benefits following CRS and HIPEC mainly depend on completeness of cytoreduction, which come at the cost of high morbidity and potential mortality. Using the acronym 'PAUSE', we aimed at describing the key imaging findings that impact surgical decision-making in patients with peritoneal mesothelioma. PAUSE stands for peritoneal cancer index, ascites and abdominal wall disease, unfavourable sites of involvement, small bowel and mesenteric disease and extraperitoneal disease. Reporting components of 'PAUSE' is crucial for patient selection. Despite limitations of CT in accurately depicting the volume of disease, describing findings in terms of PAUSE plays an important role in excluding patients who might not benefit from CRS and HIPEC. [ABSTRACT FROM AUTHOR]

Malignant mesothelioma with EWSR1-ATF1 fusion is a rare malignancy described in young adults without asbestos exposure. To the best of our knowledge, outcomes to local and systemic therapies for this subtype of malignant mesothelioma have not been described. This case report describes the clinical course of a 19-year-old man diagnosed with malignant peritoneal mesothelioma with EWSR1-ATF1 fusion localized to the abdomen. His disease followed an aggressive course and resulted in limited survival (18 mo). There was treatment resistance to several lines of conventional local and systemic treatments for peritoneal mesothelioma and biologically targeted MET inhibition with crizotinib. More research is required in this rare subtype of peritoneal mesothelioma.

Peritoneal tissue is the second most affected site by malignant mesothelioma linked to asbestos exposure. This scoping review aims to summarize the findings of the studies in which asbestos fibers in the peritoneum were quantified by electron microscopy, occasionally associated with spectroscopy, both in neoplastic and non-neoplastic tissue. The 9 studies selected comprised 62 cases, out of whom 100 samples were analyzed. Asbestos fibers were detected in 58 samples (58%). In addition, 28 cases had diagnosis of peritoneal mesothelioma. For 32 cases, a lung tumor sample was available: 28/32 samples analyzed presented asbestos fibers; 18/32 reported amphiboles with a range from not detected to 14.2 million fibers per gram of dry tissue (mfgdt); 18/32 reported chrysotile, with a range of 0 to 90 mfgdt. The studies were heterogeneous for type of samples, analytical technology, and circumstances of exposure to asbestos. To evaluate asbestos fibers in the peritoneum and to better understand the association between asbestos exposure and malignant peritoneal mesothelioma, it is desirable that the search for asbestos fibers becomes a routine process every time peritoneal tissue is accessible.