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Rationale: Schwannomas are common peripheral nerve tumors originating from Schwann cells, primarily occurring in the head and neck, limbs, and trunk. Schwannomas occurring in the mesocolon are rare and often have no specific manifestations. Abdominal schwannomas need to be differentiated from common abdominal tumors such as gastrointestinal stromal tumors., Patient Concerns: We report a case of a mesocolic schwannoma in a 59-year-old female presenting with gastrointestinal symptoms of acid reflux. At an outside hospital, gastroscopy, colonoscopy, and abdominal computed tomography scans revealed a soft tissue mass adjacent to the greater curvature of the stomach, leading to a suspicion of a gastric mesenchymal tumor., Diagnoses: Mesocolic schwannoma., Interventions: Laparoscopy was performed at our hospital. Intraoperatively, the tumor was found to be closely related to the transverse colon and was initially diagnosed as a mass originating from the transverse colon. Consequently, a resection of the mass along with the adherent portion of the transverse colon was performed. Postoperative pathology and immunohistochemistry confirmed that the tumor was a schwannoma of the mesentery and did not originate from the transverse colon., Outcomes and Lessons: Schwannomas can be distinguished from gastrointestinal stromal tumors by immunohistochemical staining, and surgical treatment is effective for benign schwannomas., Competing Interests: The authors have no conflicts of interest to disclose., (Copyright © 2024 the Author(s). Published by Wolters Kluwer Health, Inc.)

Background: Anaplastic large-cell lymphoma primarily involving the omentum is an extremely rare entity with variable clinical presentation. Owing to its rarity and nonspecific clinical manifestation, omental T-cell lymphoma is often diagnosed at a later stage, riddled with complications. While imaging modalities such as computed tomography scan can help a physician reach a diagnosis, cases that present with complications may require a multidisciplinary approach that combines surgical exploration along with consultation from Oncology., Case Presentation: We hereby report a rare case of a 66-year-old African American male patient who presented to the emergency department with complaints of acute gastrointestinal obstruction. A computed tomography scan of the abdomen and pelvis revealed evidence of an internal hernia and surgical exploration revealed a hemorrhagic and infarcted omentum. Biopsies along with immunophenotypic studies confirmed the diagnosis of anaplastic T-cell lymphoma of the omentum complicated by Massilia timonae infection., Conclusion: The case highlights the significance of considering lymphoma, although rare, as a differential in a patient who presents with small bowel obstruction and the importance of investigating for malignancy for early diagnosis and treatment of primary omental lymphomas, before complications develop., (© 2024. The Author(s).)

Tuberculosis (TB) is a serious infection that can involve any organ system and present in various forms. About one-third of the world's population are carriers of latent TB. Although most cases are from a pulmonary origin, there is a rising prevalence of abdominal TB. Patients with pulmonary or extrapulmonary TB are treated similarly through the use of pharmacological therapy. Nonspecific clinical manifestations of TB have made it difficult for clinicians to diagnose. Peritoneal tuberculosis (PTB) is a serious concern as its symptoms overlap with that of many other chronic conditions, especially in those who are immunocompromised. The lack of highly sensitive and specific testing methods has made early intervention difficult, therefore a high index of suspicion is crucial in the progression of the disease. Here, we present a case of a 71-year-old female with a history of abdominal pain, fever, and weakness. Initial investigation with computed tomography (CT) imaging revealed omental fat stranding that pointed towards peritoneal carcinomatosis (PC) from possible recurrence of her ovarian cancer. Further investigation with a peritoneal biopsy was remarkable for caseating granulomas with fat necrosis confirming extrapulmonary TB. This report highlights a rare case of PTB mimicking PC in an elderly patient who is immunocompromised from the use of long-term corticosteroids who continued to decline after pharmacological treatment of the disease., (© 2024. The Author(s).)

The NCCN Guidelines for Ovarian Cancer/Fallopian Tube Cancer/Primary Peritoneal Cancer provide multidisciplinary diagnostic workup, staging, and treatment recommendations for this disease. These NCCN Guidelines Insights detail how the evolution of the use of PARP inhibitors as maintenance and single-agent regimens for the treatment of ovarian cancer informed panel recommendations in the guidelines.

Background: Since 2016, staging laparoscopy has been implemented in the diagnostic workup of patients with gastric cancer. Staging laparoscopy aims to detect incurable disease (peritoneal metastases and irresectable tumors) and to prevent futile laparotomies., Methods: In this population-based nationwide study, we sought patient- and tumor characteristics associated with undergoing a staging laparoscopy. Additionally, we analyzed the prevalence of synchronous peritoneal metastases, the outcome of the staging laparoscopy and its clinical impact on treatment decisions. All patients diagnosed with non-cardia gastric cancer from the Netherlands Cancer Registry between 2016 and 2021 were included., Results: Alongside tumor characteristics, patient characteristics such as younger age, absence of comorbidities and lower WHO performance status were associated with performing a staging laparoscopy. In the study period, an increase in the proportion of patients who underwent a staging laparoscopy was observed, from 19.6% in 2016 to 32.3% in 2021 (p-value<0.001). In the same period, the prevalence of synchronous peritoneal metastases increased from 25% to 31%. In 37.6% of the patients who had the outcome of their staging laparoscopy reported, had incurable disease diagnosed during staging laparoscopy. Significantly less of these patients were treated with triplet regimens as compared to patients with a negative staging laparoscopy (18.5 vs. 76.3%; p-value<0.001)., Conclusion: The implementation of staging laparoscopy in gastric cancer patients paralleled the increase in diagnosis of incurable disease and a decrease in the application of triplet systemic therapies in these patients., Competing Interests: Declaration of competing interest IdH received a research grant, paid to the institute from Roche and QP&S/RanD. RV has received a research grant from Bristol Myers Squibb and performed consultancy for Daiichi Sankyo (all paid to institute). BW received a research grant from Bristol Myers Squibb and performed consultancy for BMS (all paid to institute). All remaining authors have declared no conflicts of interest., (Copyright © 2024. Published by Elsevier Ltd.)

A 77-year-old female with a subacute progression of ataxia and serum anti-Yo antibodies was suspected to have paraneoplastic cerebellar degeneration (PCD). An examination of an underlying cancer showed no abnormality in the gynecological organs, but the findings did show a mass in the Douglas fossa. The mass was resected and diagnosed as stage IIB peritoneal serous papillary carcinoma (PSPC), a rare gynecologic cancer that is difficult to diagnose in the early stages. PCD was treated with intravenous immunoglobulin (IVIG). For an early diagnosis and treatment, PSPC should be included in the list of malignancies that cause PCD with anti-Yo antibodies.

Background: PIPAC is a recent approach for intraperitoneal chemotherapy with promising results for patients with peritoneal carcinomatosis. A systematic review was conducted to assess current evidence on the efficacy and outcomes of PIPAC in patients affected by ovarian cancer., Methods: The study adhered to the PRISMA guidelines. PubMed, Google Scholar and ClinicalTrials.gov were searched up to December 2023. Studies reporting data on patients with OC treated with PIPAC were included in the qualitative analysis., Results: Twenty-one studies and six clinical trials with 932 patients who underwent PIPAC treatment were identified. The reported first access failure was 4.9%. 89.8% of patients underwent one, 60.7% two and 40% received three or more PIPAC cycles. Pathological tumour response was objectivated in 13 studies. Intra-operative complications were reported in 11% of women and post-operative events in 11.5% with a 0.82% of procedure-related mortality. Quality of life scores have been consistently stable or improved during the treatment time. The percentage of OC patients who became amenable for cytoreductive surgery due to the good response after PIPAC treatment for palliative purposes is reported to be 2.3%., Conclusion: The results showed that PIPAC is safe and effective for palliative purposes, with a good pathological tumour response and quality of life. Future prospective studies would be needed to explore the role of this treatment in different stages of the disease, investigating a paradigm shift towards the use of PIPAC with curative intent for women who are not eligible for primary cytoreductive surgery., (© 2024. The Author(s).)

Cotyledonoid dissecting leiomyoma (CDL) is a rare benign uterine leiomyoma that macroscopically shows multinodular placenta-like growth. Its border with the myometrial layer is unclear, making it clinically difficult to differentiate from uterine sarcoma. CDL is often misdiagnosed. We report a case of CDL in which a subserosal myoma was suspected preoperatively and an abdominal myomectomy was performed. However, due to intraoperative findings and intraoperative rapid histopathological diagnosis, the procedure was changed to total hysterectomy. Peritoneal dissemination had also occurred and was resected simultaneously. It has been reported that CDL is generally a disease with good prognosis and that fertility preservation may be considered depending on the case. On the other hand, some cases of large tumours have caused peritoneal dissemination. We did a literature review of CDL and compared a group with peritoneal dissemination who underwent disseminated resection simultaneously and a group without peritoneal dissemination. We found that the tumour diameter was significantly greater in the peritoneal dissemination group., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2024. No commercial re-use. See rights and permissions. Published by BMJ.)

The prognostic significance of positive peritoneal cytology still varied between cancer types and geographical origin. However, because of the lack of sensitivity of this biomarker, conventional cytology is not routinely performed in every country. Here, we wanted to test a new biomarker, peritoneal tumour DNA, using NGS technique, in order to compare it with the historical one, in patients having peritoneal metastases of gastrointestinal or ovarian cancer., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: EM – has received grant funding from BGCS, Orion Corporation, Leicester, Leicestershire and Rutland Integrated Care Board, East Genomic Medicine Service Alliance, North East London Cancer Alliance, Intuitive Surgical Ltd, East Midlands Clinical Research Network and Medical Research Council (MRC). AT − Has received financial support to attend meetings from Merck & Co., Inc (MSD). AA − None to declare. CA − None to declare. RA − None to declare. SB – Has received grants to her institution from Astrazeneca and Glaxo Smith Kline (GSK), and consulting fees from Astrazeneca, Epsilogen, GSK, Immunogen MSD, Mersana, Myriad, Novartis, Oncxerna, Seagen, Shattuck Labs, Regeneron and Verastem. She has received honoraria payments for lectures from Abbive, Astrazeneca, GSK, Immunogen, MSD, Mersnae, Pfizer, Roche, Takeda and Novacure, and financial support for attending meetings from Astrazeneca, GSK and Verastem. She is on the Ovacome advisory board (unpaid). RB – Has received honoraria for lecturers and presentations from GSK, Astra Zeneca and EISAI; support to attend meetings from GSK and PharmaAnd. She is an advisory board member for MSD, Clovis, Astra Zeneca, and GSK.She has unpaid board roles for NCRI Gynae Deputy Lead (GTGUK), UKGOM (co-chair) and is the BGCS Medical Oncology Representative. LB – is a director of Buckley Consultants Ltd. NB – Has received financial support from RanD for travel to meetings. SC – None to declare. RE – Has received consulting fees from GSK; honoraria for lecturers from GSK and Astra Zeneca and sits on the for Advisory Board for International Rainbo Study. ME-B – None to declare. CF –Has received payments for participation on a Data Safety Monitoring Board or Advisory Board for GSK, Roche, Ethicon, Astra Zeneca, MSD. JF – Has received consulting fees from ASTELLAS ASP5354 Advisory Board and is a BGCS Council member (unpaid). RG – Has received honoraria payments for lectures from Astra Zeneca, on topics unrelated to this document. AG – has received honoraria for lectrures/presentation from GSK. LH – Has received royalties from Cambridge University Press, support from Mims and Roche and Tata Medical Center to attend meetings, and is an unpaid board member to the Royal College of Radiologists. BK – Has received funding from NIHR Imperial BRC. RM – has received research grant funding from Rosetrees Trust, Barts Charity, NHS England, NHS Innovational Accelerator, Yorkshire Cancer Research and GSK. He has received honoraria from GSK and Astrazeneca for lectures and presentations. He is Chair Trial of the Steering Committee BRCA DIRECT trial, a member NICE National Standards Quality Assurance Board for Ovarian Cancer and Topic Advisor NICE Guideline – [NG241] −- Ovarian cancer: identifying and managing familial and genetic risk. He is a scientific advisor to GO Girls, BRCA Umbrella and acted on an Expert Advisory Group NHS Jewish BRCA Programme. HM – In a trustee of GO Girsls Gynaecological Cancer Charity. AM – has received National Institute for Cancer Research (NCRI) and MERCK received research funding from MDS. She has received payment from EUSA Pharma and Clovis Oncology for advisory board roles and consulting. She has recived payment from GSK for invited lectures and manuscript writing. She has received educational support and support for meeting attendance from MSD and IPSEN. TM – Project lead for NHS transformation project to embed mainstream BRCA testing into practice for breast, ovarian cancers. Nurse advisor to The EVE APPEAL gynae cancer charity. CN – None to declare. SN – has received research grants from GSK, AstraZenenca, North Central London Cancer Alliance and BGCS via her institution. She has received consulting fees from GSK, AstraZeneca and Biontech, and honoraria payments from lectures from GSK and AstraZenca. She has received financial support for attending meetings from MSD. She is an data safety monitoring/advisory board member to AstraZeneca, GSK and Biontech. She has stock options with GSK and AstraZeneca, and she is chair of the GynaeOncology Trials Group UK (previously NCRI) (unpaid). NR – None to declare. NRy – has received grants from the Chief Scientist Office Scotland (NES/CSO Postdoctoral Clinical Lectureship Scheme) and Academy of Medical Sciences to his institution. He has received honorariao payments from GSK for lectures. He is an European Hereditary Tumour Group (EHTG) Board member (unpaid). SS – has received a research grant to University of Birmingham from AoA diagnostics. She has received consultancy fees from GSK and Immunogen, and honoraria for lecturers from Astra Zeneca, Merck and GSK. She is Surgery Lead for the National Ovarian Cancer Audit, England and Wales and Co-Chair Scientific Program, International Gynaecological Cancer Society conference 2024. KV – Councillor for British Association of Gynaecological Pathology (unpaid). AW – has received honoraria for lecturers and presentaions from GSK, Astra Zeneca and Clovis. JW – is President, British Association of Gynaecological Pathologists (unpaid). JM – has received grants to her institution from the National Institute for Health and Care Research (NIHR) and MRC. She is BGCS guidelines subgroup co-chair (unpaid), sitting on BGCS Council in this role, and a NHS Cervical Screening Research Innovation and Development Advisory Committee Member (unpaid). She was an unpaid council member to Cochrane Collaboration (2019–2023) and received financial support to attend a meeting from Cochrane.

Benign mesothelial tumors are rarer than malignant mesotheliomas and are often found in the peritoneum as incidental findings in women. They include the adenomatoid tumor (AT), the well-differentiated mesothelial tumor (WDPMT), the mesothelioma in situ (MIS), and the solid papillary mesothelial tumor (SPMT). ATs are always benign and predominantly manifest in the genital tract. WDPMTs can develop multifocally and are prone to recurrence, particularly in the case of incomplete resection. Only MISs are considered a confirmed precursor lesion of malignant mesothelioma according to the currently valid World Health Organization (WHO) classifications. As with malignant mesothelioma, alterations of BAP1, MTAP, and p16 are detectable for MIS in contrast to the other three tumors. SPMTs cannot be clearly assigned to the other mesothelial tumors and have so far only been described in the peritoneum in women with a benign course., (© 2024. The Author(s), under exclusive licence to Springer Medizin Verlag GmbH, ein Teil von Springer Nature.)

Malignant peritoneal mesothelioma (MPM) is a rare and invasive tumor, and some patients will develop paraneoplastic syndrome (PS) during the course of the disease. This review summarizes PS associated with MPM, focusing on the clinical characteristics and treatment progress in hematological, endocrine, rheumatic, neurological, urinary, and other systems to decrease missed diagnosis and misdiagnosis, help early diagnosis and prompt treatment, and provide guidance for the clinical decision-making of this kind of patients., (© 2024 Wiley Periodicals LLC.)

Patients with gastric cancer peritoneal metastases (GCPM) have Stage IV disease. Systemic therapy is a crucial aspect of their care. Patients with GCPM should have their tumors tested for HER2 and PD-L1 expression and microsatellite instability for potential targeted therapies. If patients with synchronous GCPM have stable disease following neoadjuvant therapy, surgical intervention can be considered. Patients with positive cytology or low-volume peritoneal disease (peritoneal carcinomatosis index [PCI] < 7) may "convert" to negative cytology or resolution of peritoneal metastases following intraperitoneal therapy and may be candidates for subsequent gastrectomy., Competing Interests: Disclosure The authors have nothing to disclose., (Copyright © 2024 Elsevier Inc. All rights reserved.)

A free-ranging capuchin monkey developed a synchronous biphasic pleural and peritoneal mesothelioma, a rare form of this tumor. Exophytic nodules were dispersed over the serosal surfaces, showing marked microscopical malignant features composed of both epithelioid and spindeloid neoplastic cells immunopositive for Pan-Cytokeratin, Cytokeratin 5/6, Vimentin, WT-1, and D2-40., (© 2024 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Background and Aims: Pseudomyxoma peritonei (PMP) is a rare malignancy that lacks a highly sensitive and specific biomarker for its diagnosis. Identifying reliable serum markers is crucial for improving the diagnostic accuracy and management of PMP. This study aims to explore the diagnostic value of serum growth differentiation factor 15 (GDF-15) in patients with PMP., Material and Methods: We carried on a 1:1 matched case-control study. 44 patients with PMP hospitalized in Aerospace Center Hospital were recruited as cases, and 44 sex- and age-matched apparently healthy participants were selected as controls. The serum GDF-15 concentrations were tested using an ELISA method. The diagnostic value of GDF-15 in PMP patients was assessed by receiver operating characteristic (ROC) curve analysis., Results: The median serum GDF-15 level in PMP patients was 1192.77 (843.03-1879.06) pg/mL, notably higher than that in healthy controls [533.27 (410.46-641.47) pg/mL] (P<0.001). The area under the curve (AUC) of serum GDF-15 for PMP diagnosis was 0.907, the optimal diagnostic threshold value was 644.58 pg/mL, the sensitivity was 93.18 %, and the specificity was 77.27 %. The AUC of GDF-15 combined with carbohydrate antigen 125 (CA125) was larger than that of GDF-15 alone (P=0.027), and the sensitivity and specificity achieved 86.36 % and 95.45 %. GDF-15 levels showed a significant correlation with age (P=0.042), with younger PMP patients exhibiting notably lower concentrations of GDF-15 compared to older patients., Conclusion: Serum GDF-15 could become a new marker for the PMP diagnosis. The combination of GDF-15 and CA125 demonstrated superior diagnostic performance for PMP compared to GDF-15 alone, achieving a sensitivity of 86.36% and a specificity of 95.45%., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Inc.)

Multiple myeloma (MM) is a B-cell neoplasm that rounds 15% of all hematological malignancies. The typical clinical presentation of MM includes hypercalcemia, renal failure, anemia and bone lesion (CRAB). Effusions due to MM may occur due to secondary involvement of other organs and rarely are present at the initial diagnosis. Anaplastic myeloma (AMM) is rare morphological variant of multiple myeloma with predisposition of extramedullary affection. Herein, we describe a case of malignant plasmacytic ascites at disease onset of anaplastic multiple myeloma., (© 2024 Wiley Periodicals LLC.)

We aimed to present a case of two mesocolonic hydatid cysts that mimicked the presentation of peritoneal pseudomyxoma. Hydatidosis is a zoonotic parasitic infection caused by the cestode Echinococcus spp., whose larval stage affects various organs. The present case describes a 40-year-old male patient who presented with severe lower abdominal pain and was diagnosed with acute appendicitis. The patient underwent an appendectomy and was later referred to an oncology surgery clinic because of imaging findings suggestive of peritoneal pseudomyxoma or carcinomatosis. A video-assisted laparoscopic procedure revealed two cysts and microscopic findings confirmed hydatid cysts. The patient was from a hydatidosis-endemic region of southern Brazil. This case highlights the diagnostic challenges and the need for a multidisciplinary approach and careful histopathological analysis in patients with complex abdominal conditions. This also demonstrates the importance of disseminating knowledge about this condition and its management., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Inc.)

Diagnosing small bowel adenocarcinomas presents challenges due to non-specific symptoms, rarity and gastroscopy and colonoscopy's limited small intestine access, highlighting targeted diagnostic procedures' necessity. We present a late-diagnosed metastatic small bowel adenocarcinoma case in a man in his 80s who had asymptomatic mild iron-deficiency anaemia 1 year before diagnosis, with no active bleeding found on endoscopies. He experienced a single rectal bleeding episode 9 months prediagnosis, with subsequent severe iron-deficiency anaemia and no clear gastrointestinal source identified on gastroscopy. For 2 months, he had intermittent postprandial diarrhoea without abdominal pain, infectious or inflammatory causes. He experienced significant weight loss over 3 months prediagnosis. Subsequent gastroscopy indicated duodenal-gastric food retropulsion, suggesting a downstream blockage. Magnetic resonance enterography showed proximal jejunum thickening. Push enteroscopy confirmed jejunum adenocarcinoma. CT scans detected liver and peritoneal metastases. After one chemotherapy cycle, his condition worsened, leading to his passing 2 months post diagnosis., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2024. No commercial re-use. See rights and permissions. Published by BMJ.)

Pseudomyxoma peritonei (PMP) is a rare neoplastic condition characterised by gelatinous ascites, which generally arise from mucin-producing appendiceal tumours. Presentation is variable but requires prompt recognition to ensure appropriate specialist management due to risk of malignancy.A male in his 40s presented with a 1-day history of sudden onset, non-migratory abdominal pain, worse in the right iliac fossa. He had no significant medical history nor known drug allergies. Examination revealed right iliac fossa peritonism and blood tests revealed raised inflammatory markers. CT scan showed a right-sided abdominal collection. Intraoperatively, a diagnostic laparoscopy was performed, which revealed extensive mucin in the abdominal cavity. This was washed out and a laparoscopic appendectomy was performed; histopathology confirmed PMP from the ruptured appendix., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2024. No commercial re-use. See rights and permissions. Published by BMJ.)

Wolffian tumor and its nosologic relative, the recently defined STK11 adnexal tumor are rare neoplasms thought to arise from mesonephric remnants. These tumors typically arise in the broad ligament, fallopian tube, and ovarian hilum and although most are associated with a good prognosis, up to 50% of STK11 adnexal tumors demonstrate aggressive clinical behavior. The chief differential diagnoses include endometrioid adenocarcinoma and sex cord stromal tumors. However, the morphologic and immunohistochemical features of these tumors exhibit considerable overlap with peritoneal mesothelioma. To fully characterize their immunophenotypic signature, we examined a total of 21 cases (18 Wolffian and 3 STK11 adnexal tumors) with standard markers used in the diagnosis of mesothelioma. Morphologic and immunohistochemical (IHC) features were reviewed and additional IHC performed for cases with available material. Patient age ranged from 25 to 73 (mean: 51) years. Sites included adnexa/broad ligament (6, 28%), paratubal (5, 24%), ovary/paraovarian (5, 24%), tubal (intraluminal) (2, 9.5%), pelvis (2, 9.5%), and liver (1, 5%). The mean tumor size was 9.3 cm (range: 0.2 to 22 cm). The histomorphology in most cases (14/21, 66%) consisted of tubular to solid sheets of neoplastic cells lined by columnar to cuboidal cells containing uniform round to oval nuclei. Compressed tubules with slit-like lumens and sieve-like pattern were also seen in at least 7 (33%) cases. Three cases demonstrated interanastomosing cords and trabeculae of epithelioid cells with cribriform and microacinar patterns growing within prominent myxoid stroma as described in STK11 adnexal tumors. In the cases with available IHC for 3 mesothelial markers (calretinin, WT1, D2-40), 55.5% (5 of 9) showed reactivity with all 3 markers. In cases with at least 2 available mesothelial markers, 69% (11/16) were positive for 2 markers (mostly calretinin and WT1). Claudin-4, MOC31, and BER-EP4 were negative in most cases tested (78% [7/9], 71.4% [5/7], and 100% [6/6], respectively). Given the resemblance to mesothelioma, there was initial strong consideration and/or actual misdiagnosis of mesothelioma in 3 cases (14%). In summary, the morphologic and immunohistochemical features of Wolffian tumor and its recently defined relative, STK11 adnexal tumor, can lead to misdiagnosis of mesothelioma, particularly when encountered in the disseminated or metastatic setting. Wolffian tumor and STK11 adnexal tumor should be considered in the differential diagnosis of all pelvic and peritoneal mesotheliomas., Competing Interests: Conflicts of Interest and Source of Funding: T.A.L. has the disclosures: Advisory Board: Astellas, AztraZeneca, Mersana, Verastern. For the remaining authors none were declared., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Primary rectal adenocarcinoma with extensive choriocarcinomatous differentiation is a rare neoplasm, with only sporadic cases reported worldwide. The prognosis is typically poor, and no standard therapy has been established for this tumor. We report a case of a 63-year-old woman who presented with lower abdominal and pelvic discomfort, as well as rectal bleeding. Endoscopy revealed a rectal tumor. She was diagnosed with primary rectal adenocarcinoma with extensive choriocarcinomatous differentiation, accompanied by liver metastasis and peritoneal carcinomatosis. The immunohistochemical profile demonstrated strong and diffuse positivity for keratin (AE1/AE3), beta-human chorionic gonadotropin (β-HCG), p53, MYC, p16, and Ki-67. Molecular analysis indicated mutations in KRAS , TP53 , and PI3KCA . Despite the tumor's profile, the serum β-HCG level was not elevated. A chemotherapy regimen for metastatic colorectal adenocarcinoma was initiated, but there was a poor response, with rapid tumor progression. The patient survived for only 5 months postdiagnosis. We discuss the histopathological, immunohistochemical, and molecular findings, emphasizing their relevance to the differential diagnosis of neoplasms with choriocarcinomatous differentiation., Competing Interests: Declaration of Conflicting InterestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

BACKGROUND Malignant peritoneal mesothelioma (MPM) is a rare, lethal tumor of serous membranes. The most common factor reported in association with MPM is asbestos exposure, while viral infections, genetic predisposition, paraneoplastic syndrome, and altered immunity have been described as well. The diagnosis can be challenging among those with lower tumor burden as well as nonspecific symptoms, and it is not unusual to discover the diagnosis incidentally. CASE REPORT A middle-aged woman with decompensated cirrhosis underwent extensive pre-transplant workup, showing no evidence of malignancy. She had a personal history of asbestos exposure and family history of MPM in the extended family. During transplant surgery, a few peritoneal nodules were noted, leading to termination of the procedure. Pathological analysis confirmed malignant MPM. A multidisciplinary discussion led to following a conservative treatment approach without any intervention, due to higher risk of worsening hepatic decompensation associated with peritonectomy and intraperitoneal chemotherapy. The patient's hepatic decompensation resolved 6 months after the aborted liver transplant operation. Since the diagnosis of MPM, positron emission tomography scans have shown no recurrence of MPM for 3 consecutive years. CONCLUSIONS This is the first case of MPM diagnosed incidentally during a liver transplantation surgery. This case highlights the challenges in the diagnosis and management of MPM in a patient with decompensated liver disease. A multidisciplinary approach and following a consensus decision led to prolonged survival in the described patient.

Background: Pseudomyxoma peritonei (PMP) is an unusual clinical condition typically presenting with widespread mucinous neoplastic lesions within the peritoneum resulting in gelatin material-rich ascites. It was first described by Werth in 1884. Ever since, its clinical presentation, definition, site of origin, and prognosis have been a subject of debate. However, many histopathologic, immunohistochemical, and genetic studies have attempted to locate the primary lesion in the appendix in both genders., Objectives: To analyze the histological origin and survival outcomes of pseudomyxoma peritonei in patients treated at a regional cancer center., Materials and Methods: Fifteen cases of PMP were diagnosed during the five-year study period. The demographic and clinicopathological details were retrieved; the slides were reviewed and histological parameters reassessed. Descriptive statistics were used to express proportions. Continuous variables were recorded as mean (SD) or median (IQR). Kaplan-Meier (KM) curve was used to estimate overall survival., Results: Mean age for PMP was found to be 47.5 years for low grade Mucinous Carcinoma Peritonei (MCP), 54.2 years for high grade MCP, and 58 years for high grade MCP with signet ring cells. Most common overall presentation was abdominal distension in 53.3% (8/15) of cases, followed by acute appendicitis in 20% (3/15) cases. PMP was detected synchronous with the primary tumor in 9/15 cases (60%). Primary lesion in the appendix was grossly identified in 7/15 cases, while it was not explored in the remaining eight cases. Yet, by combined clinical, radiological, histopathological, and immunohistochemical analysis, we identified that most of the cases (14/15) had an appendiceal origin (93.3%). The overall survival for 12 months was 50% and for 18 months was 37%., Conclusion: The surgeon and radiologist may well bear in mind the most common possibility of an appendiceal origin for PMP and resect the appendix, irrespective of the presence of a grossly or radiologically detectable lesions. We emphasize that immunohistochemistry helped to detect the site of origin even when the primary was occult., (Copyright © 2024 Copyright: © 2024 Journal of Cancer Research and Therapeutics.)

Introduction: Biliary spillage (BS) is a common complication following initial cholecystectomy for gall bladder cancer (GBC). Few studies have explored the importance of BS as a long-term prognostic factor. We perform a meta-analysis of the association between BS and survival in GBC., Methods: A systematic literature search was performed in February 2023. Studies evaluating the incidence of BS and its association with long-term outcomes in patients undergoing initial laparoscopic or open cholecystectomy for either incidental or resectable GBC were included. Overall survival (OS), disease-free survival (DFS), and rate of peritoneal carcinomatosis (RPC) were the primary end points. Forest plot analyses were used to calculate the pooled hazard ratios (HRs) of OS, DFS, and RPC. Metaregression was used to evaluate study-level association between BS and perioperative risk factors., Results: Of 181 published articles, 11 met inclusion criteria with a sample size of 1116 patients. The rate of BS ranged between 9% and 67%. On pooled analysis, BS was associated with worse OS (HR = 1.68, 95% confidence interval [CI] = 1.32-2.14), DFS (pooled HR= 2.19, 95% CI = 1.30-3.68), and higher RPC (odds ratio = 9.37, 95% CI = 3.49-25.2). The rate of BS was not associated with higher T stage, lymph node metastasis, higher grade, positive margin status, reresection, or conversion rates., Conclusions: Our meta-analysis shows that BS is a predictor of higher peritoneal recurrence and poor survival in GBC. BS was not associated with tumor characteristics or conversion rates. Further research is needed to identify other potential risk factors for BS and investigate the ideal treatment schedule to improve survival., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Pap smears play a role in detecting extrauterine serous tumours in asymptomatic women. Certain cytopathologic and histopathologic findings combined with relevant clinical and radiologic findings indicate the possibility of primary peritoneal serous tumours. Cellblock immunohistochemistry is a valuable confirmatory diagnostic tool., (© 2024 John Wiley & Sons Ltd.)

Introduction: Peritoneal lesions cannot be definitively distinguished based on clinical and imaging characteristics alone. This study aimed to evaluate the reliability, diagnostic value, and diagnostic yield of ultrasound-guided percutaneous core needle biopsy (PCNB) for peritoneal lesions., Methods: A retrospective analysis of 129 patients who underwent PCNB for peritoneal lesions was performed to assessed technical completion and diagnostic yield., Results: The results showed that ultrasound-guided PCNB is a safe and reliable diagnostic tool with high diagnostic yield for peritoneal lesions. Technical feasibility and diagnostic yield rates were 100% and 89.9%, respectively. The diagnostic yield was lower for patients with a known history of cancer and a short anteroposterior diameter of the target lesion., Conclusions: These findings suggest that ultrasound-guided PCNB could be considered as a first-line diagnostic tool for peritoneal lesions, as it offers a minimally invasive and accurate means of obtaining tissue samples for diagnosis., (© 2024 The Author(s). Cancer Medicine published by John Wiley & Sons Ltd.)

Background: Peritoneal metastasis (PM) is the most prevalent type of metastasis in patients with gastric cancer (GC) and has an extremely poor prognosis. The detection of free cancer cells (FCCs) in the peritoneal cavity has been demonstrated to be one of the worst prognostic factors for GC. However, there is a lack of sensitive detection methods for FCCs in the peritoneal cavity. This study aimed to use a new peritoneal lavage fluid cytology examination to detect FCCs in patients with GC, and to explore its clinical significance on diagnosing of occult peritoneal metastasis (OPM) and prognosis., Methods: Peritoneal lavage fluid from 50 patients with GC was obtained and processed via the isolation by size of epithelial tumor cells (ISET) method. Immunofluorescence and fluorescence in situ hybridization (FISH) were used to identify FCCs expressing chromosome 8 (CEP8), chromosome 17 (CEP17), and epithelial cell adhesion molecule (EpCAM)., Results: Using a combination of the ISET platform and immunofluorescence-FISH, the detection of FCCs was higher than that by light microscopy (24.0% vs . 2.0%). Samples were categorized into positive and negative groups, based on the expressions of CEP8, CEP17, and EpCAM. Statistically significant relationships were demonstrated between age ( P = 0.029), sex ( P = 0.002), lymphatic invasion ( P = 0.001), pTNM stage ( P = 0.001), and positivity for FCCs. After adjusting for covariates, patients with positive FCCs had lower progression-free survival than patients with negative FCCs., Conclusion: The ISET platform highly enriched nucleated cells from peritoneal lavage fluid, and indicators comprising EpCAM, CEP8, and CEP17 confirmed the diagnosis of FCCs. As a potential detection method, it offers an opportunity for early intervention of OPM and an extension of patient survival., Competing Interests: The authors declare that they have no competing interests., (© 2024 Xuan et al.)

Background: Pseudomyxoma peritonei is an infrequent condition with a global annual incidence of only one to two cases per million people. Mucinous neoplasms, widespread intraperitoneal implants, and mucinous ascites characterize it. Currently, most clinicians misdiagnose this condition, which leads to delayed management., Case Presentation: A 44-year-old North Indian female presented with a 1.5-month history of an abdominal lump. Physical examination revealed a sizeable abdominopelvic mass at 36 weeks. Contrast-enhanced computed tomography showed a massive multiloculated right ovarian cystic mass measuring 28 × 23 × 13 cm with mild ascites and elevated carcinoembryonic antigen levels (113.75 ng/ml). A provisional diagnosis of ovarian mucinous neoplasm was made, for which the patient underwent laparotomy. Intraoperatively, there were gross mucinous ascites, along with a large, circumscribed, ruptured right ovarian tumor filled with gelatinous material. The appendicular lump was also filled with mucinous material along with the omentum, ascending colon, right lateral aspect of the rectum, splenic surface, and small bowel mesentery. Cytoreductive surgery was performed along with an oncosurgeon, including total abdominal hysterectomy with bilateral salpingoophorectomy, omentectomy, right hemicolectomy, lower anterior resection, ileo-transverse stapled anastomosis with proximal ileal loop diversion stoma, excision of multiple peritoneal gelatinous implants, and peritoneal lavage. Histopathology and immunohistochemistry confirmed the presence of intestinal-type mucinous carcinoma. Postoperatively, the patient was given six cycles of chemotherapy. She tolerated it without any specific morbidity and had an uneventful recovery. Postoperative follow-up at 15 months revealed normal tumor marker levels and abdominal computed tomography findings and no signs suggestive of local recurrence or distal metastases., Conclusions: Pseudomyxoma peritonei is a rare disease that is frequently misdiagnosed in the preoperative phase. Therefore, radiologists and clinicians should maintain a high index of suspicion for accurate diagnosis and multidisciplinary management., (© 2024. The Author(s).)

The prevalence and fatality rates of gastric cancer (GC) remain elevated, with advanced stages presenting a grim prognosis. Noninvasive diagnosis of GC cancer often proves challenging until the disease has progressed to an advanced stage or metastasized. Initially, the level of fibronectin (FN) in cancer-associated fibroblasts (CAFs) of GC was at least 3.7 times higher than that in normal fibroblasts. Herein, two FN-targeting magnetic resonance/near-infrared fluorescence (MR/NIRF) imaging contrast agents were developed to detect GC and peritoneal metastasis noninvasively. The probes CREKA-Cy7-(Gd-DOTA) and CREKA-Cy7-(Gd-DOTA) 3 demonstrated significant FN-targeting capability (with dissociation constants of 1.0 and 2.1 mM) and effective MR imaging performance (with proton relaxivity values of 9.66 and 27.44 mM -1 s -1 at 9.4 T, 37 °C). In vivo imaging revealed a high signal-to-noise ratio and successful visualization of GC metastasis using NIRF imaging as well as successful tumor detection in MR imaging. Therefore, this study highlights the potential of FN-targeting probes for GC diagnosis and aids in the advancement of new diagnostic strategies for the clinical detection of GC.

Disseminated peritoneal leiomyomatosis (DPL) is a rare and benign clinical entity. It is also known as leiomyomatosis peritonealis disseminata (LPD). Here, we report and discuss a case of a primiparous woman in her early 40s who presented with heavy, prolonged, painful menses and heaviness in her lower abdomen. She underwent a laparoscopic myomectomy for a fibroid uterus, 12 months ago for similar complaints. On workup, she was diagnosed with DPL. We performed a total abdominal hysterectomy with bilateral salpingectomy, low anterior resection with stapled colorectal anastomosis and excision of peritoneal tumour deposits in consortium with the gastrosurgery team. Her postoperative period was uneventful, and the patient was discharged on postop day 6. Her histopathology report was consistent with leiomyoma; the follow-up period was uneventful., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2024. No commercial re-use. See rights and permissions. Published by BMJ.)

A 46-year-old female presented persistent right lower abdominal pain for 4 days. Computed tomography revealed an enlarged appendix with a surrounding low-attenuation mass. The patient was diagnosed with appendiceal abscess-forming appendicitis and initially treated with antibiotics. However, owing to the manifestation of nausea as a side effect, laparoscopic appendectomy was performed 3 days after the initial consultation. Intraoperative examination revealed mucinous material on the surface of the appendix and within the abdominal cavity, leading to the decision to perform an appendectomy with partial cecum resection and excision of the omentum with mucinous deposits. Pathological examination confirmed the diagnosis of a perforating low-grade appendiceal mucinous neoplasm and pseudomyxoma peritonei. The patient was subsequently referred to a specialized center for ongoing management, and at 9 months postoperatively, surveillance is being conducted. Low-grade appendiceal mucinous neoplasms can progress to pseudomyxoma peritonei through perforation; however, an optimal treatment approach has not yet been established. In particular, patients in advanced stages of the disease often require challenging management decisions. This case is reported along with a review of the literature to provide further guidance.

Detection of peritoneal dissemination (PD) in gastric cancer (GC) patients remains challenging. The feasibility of tumor-guided cell-free DNA (cfDNA) detection in prospectively collected peritoneal fluid (ascites and peritoneal lavage) was investigated and compared to conventional cytology in 28 patients. Besides conventional cytology, next generation sequencing was performed on primary tumor DNA and cell-free DNA from peritoneal fluid. Patients were retrospectively grouped into: a positive group (with PD) and a negative group (without PD). Detectable mutations were found in the primary tumor of 68% (n = 19). Sensitivity of PD detection by tumor-guided cfDNA analysis was 91%, compared to 64% by conventional cytology. Within the positive group (n = 11), tumor-guided cfDNA was detected in all patients with ascites samples (4/4, 100%) and in 86% (6/7) of the lavage samples, opposed to 4/4 (100%) patients with ascites and 43% (3/7) with lavage by conventional cytology. Within the negative group (n = 8), conventional cytology was negative for all samples. In two patients, tumor-guided cfDNA was detected in peritoneal lavage fluid. Interestingly, these 2 patients developed PD within 6 months, suggesting a prognostic value of tumor-guided cfDNA detection. This study showed that tumor-guided cfDNA detection in peritoneal fluids of GC patients is feasible and superior to conventional cytology in detecting PD., (© 2024. The Author(s), under exclusive licence to Springer Nature Limited.)

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.

Background: Our aim was to investigate utility of indocyanine green (ICG) and autofluorescence (AF) imaging in detection of small bowel primary and metastatic carcinoids., Methods: Using Institutional Review Board approval, ICG and AF imaging of small bowel carcinoids was performed. Imaging findings were prospectively recorded in operating room and compared with conventional imaging, surgical exploration and pathologic findings., Results: There were 16 patients with 23 primary small bowel tumors, 27 mesenteric lymph nodes, 36 liver metastases and 2 peritoneal nodules. Carcinoid tumors exhibited brighter AF signals compared to background. AF imaging was superior to both DOTATATE PET and surgeon inspection/palpation in demonstrating small bowel primaries. Utility for metastatic lymph nodes and peritoneal metastases was limited. Superficial liver metastases exhibited brighter fluorescence compared to background on both ICG and AF imaging., Conclusions: This is the largest study assessing utility of near-infrared fluorescence imaging in detection of small bowel carcinoids. Our results show promise in the utilization fluorescence imaging to detect occult primary tumors and superficial liver metastases., Competing Interests: Declaration of competing interest Dr. Berber has unrelated consulting agreements with Aesculap, Ethicon, Intuitive, and Medtronic. He has received honoraria for consulting work unrelated to this study. He also established a consulting agreement with Fluoptics in April 2023 to participate in an educational activity and has received honoraria. The other authors do not have any conflicts to declare., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Background: Plasma circulating tumor DNA (ctDNA) is a promising biomarker for metastatic colorectal cancer (mCRC); however, its role in characterizing recurrence sites after mCRC resection remains poorly understood. This single-institution study investigated the timing of ctDNA detection and its levels in the context of recurrence at different sites after mCRC resection., Study Design: Patients who underwent optimal resection of CRC metastases involving the peritoneum, distant lymph nodes, or liver, with serial postoperative tumor-informed ctDNA assessments (Signatera) were included. Recurrence sites, as defined by surveillance imaging or laparoscopy, were categorized as peritoneal-only and other distant sites (liver, lung, lymph nodes, or body wall)., Results: Among the 31 included patients, ctDNA was detected in all 26 (83.4%) patients with postoperative recurrence and was persistently undetectable in 5 patients who did not experience recurrence. At 3 months postsurgery, ctDNA was detected in 2 (25%) of 8 patients with peritoneal-only recurrence and 17 (94.4%) of 18 patients with distant recurrence (p < 0.001). Beyond 3 months, ctDNA was detected in the remaining 6 patients with peritoneal-only disease and 1 patient with distant disease. ctDNA detection preceded the clinical diagnosis of recurrence by a median of 9 weeks in both groups. At recurrence, peritoneal-only recurrent cases exhibited lower ctDNA levels (median 0.4 mean tumor molecules/mL, interquartile range 0.1 to 0.8) compared with distant recurrence (median 5.5 mean tumor molecules/mL, interquartile range 0.8 to 33.3, p = 0.004)., Conclusions: Peritoneal-only recurrence was associated with delayed ctDNA detection and low levels of ctDNA after optimal resection for mCRC. ctDNA testing may effectively characterize recurrence sites and may help guide subsequent treatments specific to the disease sites involved., (Copyright © 2024 by the American College of Surgeons. Published by Wolters Kluwer Health, Inc. All rights reserved.)

BACKGROUND Malignant peritoneal mesothelioma is a rare disease with a poor prognosis that often presents with vague symptoms and inconclusive laboratory test results. Causes include industrial pollutants, primarily asbestos, and certain genetic mutations, such as BAP1. Due to the nonspecific symptoms, it is often incidentally diagnosed during or after other surgical procedures. CASE REPORT A 35-year-old healthy woman underwent an uncomplicated laparoscopic left salpingo-oophorectomy for a symptomatic large ovarian mature cystic teratoma. She subsequently presented with late-onset postoperative fever, leukocytosis, and multiple intra-abdominal masses. Following an exploratory laparotomy, extensive infectious disease evaluation, and multiple biopsies requiring interdisciplinary collaboration, malignant peritoneal mesothelioma was diagnosed by positive histologic staining of an omental biopsy for D2-40 and CK5/6. This first specimen was positive for BAP1, with the second, a liver biopsy, testing negative for BAP1. The tumor cell testing was also notable for mutations in NF2, MLL2, and ARID1A, and the hereditary cancer genetic testing was overall unremarkable. Her disease progressed rapidly, and she died 6 months after her initial procedure. CONCLUSIONS This case of rapidly developing malignant peritoneal mesothelioma following surgical management of an ovarian mature teratoma highlights the complexity in diagnosing a rare disease that presents with nonspecific symptoms in an otherwise young and healthy woman. The rapid disease course was likely accelerated by expansive intraperitoneal spread and multiple somatic oncogenic mutations in BAP1, NF2, MLL2, and ARID1A. Gynecologists should keep a broad differential for postoperative complications, as occult malignancies can present with symptoms that mimic postoperative complications.

Competing Interests: None declared.