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Background: Decision regret is an emerging patient reported outcome. The aim of this study was to assess the incidence of regret in patients with appendiceal cancer (AC) who underwent cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS-HIPEC). Patients and Methods: An anonymous survey was distributed to patients through the Appendix Cancer and Pseudomyxoma Peritonei (ACPMP) Research Foundation. The Decision Regret Scale (DRS) was employed, with DRS > 25 signifying regret. Patient demographics, tumor characteristics, postoperative outcomes, symptoms (FACT-C), and PROMIS-29 quality of life (QoL) scores were compared between patients who regretted or did not regret (NO-REG) the procedure. Results: A total of 122 patients were analyzed. The vast majority had no regret about undergoing CRS-HIPEC (85.2%); 18 patients expressed regret (14.8%). Patients with higher regret had: income ≤ $74,062 (72.2% vs 44.2% NO-REG; p = 0.028), major complications within 30 days of surgery (55.6% vs 15.4% NO-REG; p < 0.001), > 30 days hospital stay (38.9% vs 4.8% NO-REG; p < 0.001), a new ostomy (27.8% vs 7.7% NO-REG; p = 0.03), >1 CRS-HIPEC procedure (56.3% vs 12.6% NO-REG; p < 0.001). Patients with worse FACT-C scores had more regret (p < 0.001). PROMIS-29 QOL scores were universally worse in patients with regret. Multivariable analysis demonstrated > 30 days in the hospital, new ostomy and worse gastrointestinal symptom scores were significantly associated with regret. Conclusions: The majority of patients with AC undergoing CRS-HIPEC do not regret undergoing the procedure. Lower income, postoperative complications, an ostomy, undergoing > 1 procedure, and with worse long-term gastrointestinal symptoms were associated with increased regret. Targeted perioperative psychological support and symptom management may assist to ameliorate regret. [ABSTRACT FROM AUTHOR]

Objective: Currently, the primary surgical treatment for pseudomyxoma peritonei (PMP) is cytoreductive surgery (CRS) combined with hyperthermic intraperitoneal chemotherapy (HIPEC). The perioperative period is frequently accompanied by severe pain. Erector spinae plane block (ESPB) can enhance analgesia for abdominal surgery. The purpose of this study was to compare the analgesic effects of bilateral multiple-injection ESPB in patients with PMP. Methods: Fifty patients with PMP were randomly divided into two groups: the ESPB combined with general anesthesia group (Group E) and the general anesthesia alone group (Group C). Prior to the induction, patients in Group E underwent ESPB at the T7 and T11 levels. The primary outcome was the visual analog scale (VAS) scores during rest at 6 h post-extubation. Secondary outcomes included intraoperative and postoperative opioid consumption, time for first rescue analgesia, frequency distribution of rescue analgesia, incidence of nausea and vomiting, adverse events associated with ESPB. Results: The Visual Analogue Scale (VAS) scores in Group E were significantly lower compared to Group C at immediate post-extubation (1.6 ± 0.9 vs. 2.4 ± 1.2, P = 0.008), and at 2 (1.9 ± 1.2 vs. 3.2 ± 1.1, P < 0.001), 4 (2.4 ± 1.5 vs. 3.7 ± 1.0, P = 0.001), and 6 h (2.7 ± 1.1 vs. 3.8 ± 1.4, P = 0.004) post-extubation during rest. Similarly, the VAS scores in Group E were significantly lower than those in Group C at immediate post-extubation (3.0 ± 1.4 vs. 4.6 ± 1.2, P < 0.001), and at 2 (3.8 ± 1.7 vs. 4.9 ± 1.4, P = 0.019), 4 (3.5 ± 1.3 vs. 5.3 ± 1.5, P < 0.001), and 6 h (3.9 ± 1.8 vs. 4.9 ± 1.3, P = 0.004) post-extubation during movement. In Group E, the intraoperative remifentanil administration (2319.3 ± 1089.5 vs. 2984.6 ± 796.1, P = 0.017) and the amount of rescue analgesia within 2 h post-extubation (0 vs. 4, P = 0.037) were significantly less than in Group C, and the first rescue analgesia time was shorter as well (231.4 ± 147.5 vs. 668.8 ± 416.7, P < 0.001). Conclusion: Compared to general anesthesia alone, bilateral multiple-injection ESPB with 0.2% ropivacaine can enhance analgesia and reduce opioid administration in patients with PMP. However, the duration of analgesia with ESPB is relatively short due to the low concentration of the local anesthetic used. Trial registration: Chinese Clinical Trial Registry, ChiCTR2300069504, 20/03/2023. [ABSTRACT FROM AUTHOR]

Background: The combination of cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) constitutes the established standard of care for pseudomyxoma peritonei patients. However, the role of HIPEC lacks validation through randomized trials, leading to diverse proposed treatment protocols. This consensus seeks to standardize HIPEC regimens and identify research priorities for enhanced clarity. Methods: The steering committee applied the patient, intervention, comparator, and outcome method to formulate crucial clinical questions. Evaluation of evidence followed the Grading of Recommendations, Assessment, Development, and Evaluation system. Consensus on HIPEC regimens and research priorities was sought through a two-round Delphi process involving international experts. Results: Out of 90 eligible panelists, 71 (79%) participated in both Delphi rounds, resulting in a consensus on six out of seven questions related to HIPEC regimens. An overwhelming 84% positive consensus favored combining HIPEC with CRS, while a 70% weak positive consensus supported HIPEC after incomplete CRS. Specific HIPEC regimens also gained consensus, with 53% supporting Oxaliplatin 200 mg/m2 and 51% favoring the combination of cisplatin (CDDP) associated with mitomycin-C (MMC). High-dose MMC regimens received an 89% positive recommendation. In terms of research priorities, 61% of panelists highlighted the importance of studies comparing HIPEC regimens post CRS. The preferred regimens for such studies were the combination of CDDP/MMC and high-dose MMC. Conclusions: The consensus recommends the application of HIPEC following CRS based on the available evidence. The combination of CDDP/MMC and high-dose MMC regimens are endorsed for both current clinical practice and future research efforts. [ABSTRACT FROM AUTHOR]

Abstract Background Pseudomyxoma peritonei (PMP) is a rare malignant peritoneal tumor that readily recurs and metastasizes. Studies have shown that cancer stem cells (CSCs) play an important role in tumor recurrence, metastasis, and prognosis. Objective In this study, our aim was to isolate CSCs from various tissues of PMP patients and compare their proliferation, migration, and anti-inflammatory abilities. Methods We identified CSCs subsets with markers CD133+, CD166+, and CD133+/CD166+ at the gene level using single-cell mRNA sequencing (scRNA-seq). Appendiceal CSCs (AC), peritoneal CSCs (PC), and mucous CSCs (MC) were obtained using MACSQuant Tyto sorting technology and FlowSight imaging flow cytometry. The cells were cultured and markers were identified. Finally, the functional phenotypes of the three cell types were compared. Results CSCs content was highest in the appendiceal tumor tissue and lowest in the mucous tissue. The cell viability rate of the sorted CSCs was above 98%, and the positive rate of CD133+ and CD166+ was 70–80%, and CD133+/CD166+ was about 30%. Among the three types of CSCs, MC had the highest proliferation ability, and TNF-α has the greatest inhibitory effect on AC migration. Conclusion AC in patients was more inert and anti-inflammatory, whereas abdominal cavity MC and PC were more active. This study revealed the biological characteristics of CSCs in different tumor tissues of patients with PMP, providing a reference for future targeted CSCs therapy.

Abstract Objective Currently, the primary surgical treatment for pseudomyxoma peritonei (PMP) is cytoreductive surgery (CRS) combined with hyperthermic intraperitoneal chemotherapy (HIPEC). The perioperative period is frequently accompanied by severe pain. Erector spinae plane block (ESPB) can enhance analgesia for abdominal surgery. The purpose of this study was to compare the analgesic effects of bilateral multiple-injection ESPB in patients with PMP. Methods Fifty patients with PMP were randomly divided into two groups: the ESPB combined with general anesthesia group (Group E) and the general anesthesia alone group (Group C). Prior to the induction, patients in Group E underwent ESPB at the T7 and T11 levels. The primary outcome was the visual analog scale (VAS) scores during rest at 6 h post-extubation. Secondary outcomes included intraoperative and postoperative opioid consumption, time for first rescue analgesia, frequency distribution of rescue analgesia, incidence of nausea and vomiting, adverse events associated with ESPB. Results The Visual Analogue Scale (VAS) scores in Group E were significantly lower compared to Group C at immediate post-extubation (1.6 ± 0.9 vs. 2.4 ± 1.2, P = 0.008), and at 2 (1.9 ± 1.2 vs. 3.2 ± 1.1, P

Intrabdominal dissemination of malignant mesothelioma (MM) and pseudomyxoma peritonei (PMP) is poorly characterized with respect to the stemness window which malignant cells activate during their reshaping on the epithelial‐mesenchymal (E/M) axis. To gain insights into stemness properties and their prognostic significance in these rarer forms of peritoneal metastases (PM), primary tumor cultures from 55 patients selected for cytoreductive surgery with hyperthermic intraperitoneal chemotherapy were analyzed for cancer stem cells (CSC) by aldehyde dehydrogenase 1 (ALDH1) and spheroid formation assays, and for expression of a set of plasticity‐related genes to measure E/M transition (EMT) score. Intratumor heterogeneity was also analyzed. Samples from PM of colorectal cancer were included for comparison. Molecular data were confirmed using principal component and cluster analyses. Associations with survival were evaluated using Kaplan–Meier and Cox regression models. The activity of acetylsalicylic acid (ASA), a stemness modifier, was tested in five cultures. Significantly increased amounts of ALDH1bright‐cells identified high‐grade PMP, and discriminated solid masses from ascitic/mucin‐embedded tumor cells in both forms of PM. Epithelial/early hybrid EMT scores and an early hybrid expression pattern correlated with pluripotency factors were significantly associated with early peritoneal progression (p =.0343 and p =.0339, respectively, log‐rank test) in multivariable models. ASA impaired spheroid formation and increased cisplatin sensitivity in all five cultures. These data suggest that CSC subpopulations and hybrid E/M states may guide peritoneal spread of MM and PMP. Stemness could be exploited as targetable vulnerability to increase chemosensitivity and improve patient outcomes. Additional research is needed to confirm these preliminary data. [ABSTRACT FROM AUTHOR]

Cytoreductive surgery (CRS) with or without hyperthermic intraperitoneal chemotherapy (HIPEC) is the mainstay of potentially curative surgical treatment for malignancies that have spread to peritoneal surfaces. This surgical procedure is however associated with high morbidity and appropriate patient selection and planning is therefore essential. Available multimodality imaging techniques include CT with oral and intravenous contrast, MRI including use of dedicated peritoneal protocol and FDG-PET/CT. These used with the correct technique, read by specialist radiologists and discussed under the auspices of a dedicated multidisciplinary team, can help to improve outcomes. We demonstrate that imaging not only provides information about peritoneal disease burden but more importantly want to shift the reader's focus to disease distribution. Our examples highlight how imaging helps avoid futile surgery by identifying patients with disease in unfavourable sites and show the strength and limitations of the various imaging modalities. We share how MR imaging can help identify multifocal and often occult sites including widespread miliary disease. Our examples provide a comprehensive overview demonstrating how imaging can help plan surgery by identifying patients who may need splenic vaccinations, counselling for stoma, egg harvesting and input from surgeons with other specialist expertise greatly increasing likelihood of achieving complete cytoreduction. [ABSTRACT FROM AUTHOR]

Background: International consensus on classifications of appendiceal mucinous neoplasms (AMNs) and associated pseudomyxoma peritonei (PMP) have been carefully made but clinicopathological associations supporting decision making remain scarce. Objective: This study aimed to assess interdependence between AMNs and PMP and provide directions for clinical management. Methods: This two-center retrospective cohort study reviewed patients with PMP treated with cytoreductive surgery and hyperthermic intraperitoneal chemotherapy between 2005 and 2021. The primary objective was to reassess histopathologic grade of AMNs and PMP according to the Peritoneal Surface Oncology Group International classification and to establish its interdependence. Secondary outcomes were recurrence rate, PMP grade progression, ovarian involvement, and overall survival (OS). Results: Of 105 patients included, 78 (74.3%) had low-grade AMNs as the primary tumor, 8 (7.6%) had high-grade AMNs, 7 (6.7%) had mucinous adenocarcinoma (MAC), 1 (0.9%) had MAC with signet ring cells (SRC), and 11 (10.5%) had unidentified tumors. Overall, 11 patients (10.5%) had no PMP, 21 (20.0%) had acellular mucin, 56 (53.3%) had low-grade PMP, 12 (11.4%) had high-grade PMP, and 5 (4.8%) had PMP-SRC. In 11 cases (13.3%), AMNs and matching PMP grade differed. Over a 16-year follow-up, recurrence occurred in 31.8%, with three cases showing histopathologically changed PMP. Ovarian involvement was observed in 43/65 females (66.2%). Median OS was 13.8 years, and 5-year OS rates were 100%, 74.4%, 44.4%, and 20% for acellular mucin, low-grade PMP, high-grade PMP and PMP-SRC, respectively (p < 0.001). Conclusions: AMN histology does not always reflects its associated PMP grade, while PMP grade strongly influences survival. Ovarian involvement and recurrent PMP showing unchanged histopathological features are common. [ABSTRACT FROM AUTHOR]

Pseudomyxoma peritonei (PMP) is a relatively uncommon condition primarily associated with neoplasms of the appendiceal epithelium. It is characterized by non-specific clinical manifestations, leading to a high rate of misdiagnosis. This report describes the case of a 62-year-old male patient with recurrent and metastatic PMP. The patient first experienced unexplained epigastric pain and paroxysmal abdominal pain accompanied by distension over 8 years ago. He underwent surgical interventions for the condition in other hospitals in 2015 and 2018, respectively.

Pseudomyxoma peritonei (PMP) is an indolent malignant syndrome. The standard treatment for PMP is cytoreductive surgery combined with intraperitoneal hyperthermic chemotherapy (CRS + HIPEC). However, the high recurrence rate and latent clinical symptoms and signs are major obstacles to further improving clinical outcomes. Moreover, patients in advanced stages receive little benefit from CRS + HIPEC due to widespread intraperitoneal metastases. Another challenge in PMP treatment involves the progressive sclerosis of PMP cell-secreted mucus, which is often increased due to activating mutations in the gene coding for guanine nucleotide-binding protein alpha subunit ( GNAS ). Consequently, the development of other PMP therapies is urgently needed. Several immune-related therapies have shown promise, including the use of bacterium-derived non-specific immunogenic agents, radio-immunotherapeutic agents, and tumor cell-derived neoantigens, but a well-recognized immunotherapy has not been established. In this review the roles of GNAS mutations in the promotion of mucin secretion and disease development are discussed. In addition, the immunologic features of the PMP microenvironment and immune-associated treatments are discussed to summarize the current understanding of key features of the disease and to facilitate the development of immunotherapies.

Abstract Background Cytoreductive surgery (CRS) combined with hyperthermic intraperitoneal chemotherapy (HIPEC) is established in the management of pseudomyxoma peritonei (PMP), selected cases of peritoneal mesothelioma, and resectable colorectal or ovarian peritoneal metastases in Western countries. However, the efficacy and feasibility of these techniques are not well established in the Asian population, and little has been reported on long‐term survival outcomes for surgically resected PMP patients. Materials and Methods Retrospective analysis of a prospective database of short‐ and longer‐term outcomes of consecutive patients who underwent CRS and HIPEC for PMP in a newly established peritoneal malignancy unit in Japan between 2010 and 2016. Results A total of 105 patients underwent CRS and HIPEC and 57 maximal tumor debulking (MTD) for pseudomyxoma peritonei. In the CRS group, the primary tumor was appendiceal in 94 patients (90%) followed by ovarian and colorectal. Major postoperative complications occurred in 22/105 patients (21%) with one in‐hospital mortality (0.9%). The 5‐year overall and disease‐free survival rates for the CRS group were 74.2% and 50.1%, respectively. Multivariate analysis revealed unfavorable histology to be the significant predictor of reduced overall and disease‐free survival. Completeness of cytoreduction, CA19‐9, and CA125 were also associated with disease‐free survival. Conclusions This is the first report on long‐term outcomes and survival analysis of CRS and HIPEC for PMP in the Asian population. CRS and HIPEC can be conducted with reasonable safety and favorable survival in a new center. Complete tumor removal and histological type are the strongest prognostic factors for both overall and disease‐free survival.

Abstract 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.

Appendiceal mucinous neoplasms are rare and can be associated with the development of disseminated peritoneal disease known as pseudomyxoma peritonei (PMP). Mucinous tumours identified on appendicectomy are therefore followed up to assess for recurrence and the development of PMP. In addition, individuals who initially present with PMP and are treated with cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS/HIPEC) are followed up to assess for recurrence. However, despite the concerted efforts of multiple expert groups, the optimal imaging follow-up protocol is yet to be established. The purpose of this article is to review the available evidence for imaging surveillance in these populations to identify the optimum post-resection imaging follow-up protocol. [ABSTRACT FROM AUTHOR]

Pseudomyxoma peritonei (PMP) is a well‐known entity in gastrointestinal and ovarian tumors of mucinous histology. It has important implications on prognosis depending on whether seen in conjunction with a benign or a malignant tumor. In the current report, we describe a case of PMP in a case of advanced endocervical adenocarcinoma of the cervix which was managed surgically. [ABSTRACT FROM AUTHOR]

Introduction: Pseudomyxoma peritonei (PMP) is a disease characterized by progressive accumulation of intraperitoneal mucinous ascites produced by neoplasms in the abdominal cavity. Since the prognosis of patients with PMP remains unsatisfactory, the development of effective therapeutic drug(s) is a matter of pressing concern. Genetic analyses of PMP have clarified the frequent activation of GNAS and/or KRAS. However, the involvement of global epigenetic alterations in PMPs has not been reported. Methods: To clarify the genetic background of the 15 PMP tumors, we performed genetic analysis using AmpliSeq Cancer HotSpot Panel v2. We further investigated global DNA methylation in the 15 tumors and eight noncancerous colonic epithelial tissues using MethylationEPIC array BeadChip (Infinium 850k) containing a total of 865,918 probes. Results: This is the first report of comprehensive DNA methylation profiles of PMPs in the world. We clarified that the 15 PMPs could be classified into at least two epigenotypes, unique methylation epigenotype (UME) and normal-like methylation epigenotype (NLME), and that genes associated with neuronal development and synaptic signaling may be involved in the development of PMPs. In addition, we identified a set of hypermethylation marker genes such as HOXD1 and TSPYL5 in the 15 PMPs. Conclusions: These findings may help the understanding of the molecular mechanism(s) of PMP and contribute to the development of therapeutic strategies for this life-threatening disease. [ABSTRACT FROM AUTHOR]

Simple Summary: This study aimed to assess the prognostic role of circulating tumor cells (CTCs) in patients with epithelial appendiceal neoplasms with peritoneal metastases. The presence of CTCs may be used for the early detection of invasive cancer in this rare diagnosis. Our study is the first study to assess the potential value of CTCs in this specific group of patients. Appendiceal tumors are uncommon and, at times, discovered incidentally during histological examination. The histopathological classification of the disease is complex and has generated some controversy. The analysis of circulating tumor cells can be used for the early detection of metastatic potential. The aim of the present study was to examine the prognostic value of circulating tumor cells in patients with appendiceal tumors and peritoneal metastases. To our knowledge, this is the first study to examine CTCs in appendiceal tumors. We performed a prospective cohort study of consecutive patients treated with cytoreductive surgery and hyperthermic intraperitoneal chemotherapy between 2015 and 2019 at a HIPEC referral center. In total, 31 patients were included in the analysis, and circulating tumor cells were detected in 15 patients (48%). CTC positivity was not associated with overall or recurrence-free survival, nor was it correlated with PCI score or histopathological grading. Surprisingly, however, CTCs were found in almost half the patients. The presence or quantities of these cells did not, on their own, predict systemic metastatic potential during the observed time, and they did not appear to significantly correlate with the oncological outcomes recorded. [ABSTRACT FROM AUTHOR]

Background: Cytoreductive surgery (CRS) combined with hyperthermic intraperitoneal chemotherapy (HIPEC) is established in the management of pseudomyxoma peritonei (PMP), selected cases of peritoneal mesothelioma, and resectable colorectal or ovarian peritoneal metastases in Western countries. However, the efficacy and feasibility of these techniques are not well established in the Asian population, and little has been reported on long‐term survival outcomes for surgically resected PMP patients. Materials and Methods: Retrospective analysis of a prospective database of short‐ and longer‐term outcomes of consecutive patients who underwent CRS and HIPEC for PMP in a newly established peritoneal malignancy unit in Japan between 2010 and 2016. Results: A total of 105 patients underwent CRS and HIPEC and 57 maximal tumor debulking (MTD) for pseudomyxoma peritonei. In the CRS group, the primary tumor was appendiceal in 94 patients (90%) followed by ovarian and colorectal. Major postoperative complications occurred in 22/105 patients (21%) with one in‐hospital mortality (0.9%). The 5‐year overall and disease‐free survival rates for the CRS group were 74.2% and 50.1%, respectively. Multivariate analysis revealed unfavorable histology to be the significant predictor of reduced overall and disease‐free survival. Completeness of cytoreduction, CA19‐9, and CA125 were also associated with disease‐free survival. Conclusions: This is the first report on long‐term outcomes and survival analysis of CRS and HIPEC for PMP in the Asian population. CRS and HIPEC can be conducted with reasonable safety and favorable survival in a new center. Complete tumor removal and histological type are the strongest prognostic factors for both overall and disease‐free survival. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Low-grade appendiceal mucinous neoplasms (LAMNs) are rare and heterogeneous diseases that, despite their increased incidence, are well differentiated, tend to be painless, and histologically lack distinctive invasive features without infiltrative growth, destructive infiltration, or associated profibroproliferative responses. However, the biological behaviour of these tumours is difficult to determine preoperatively or intraoperatively, and the possibility of rupture puts patients at risk for peritoneal pseudomucinous neoplasms (PMPs). Patients with low-grade appendiceal mucinous tumours and peritoneal pseudomucinous tumours experience slow disease progression and are incurable and have a high risk of recurrence, morbidity, and ultimately death, despite the reported 5- and 10-year survival rates of 50-86% and 45-68%, respectively. In this article, we report the case of a 80-year-old male with a giant low-grade appendiceal mucinous tumour associated with a peritoneal pseudomucinous tumour, and discuss the diagnostic and management strategies for giant lowgrade appendiceal mucinous tumours in the context of a literature review. [ABSTRACT FROM AUTHOR]

Simple Summary: Routine resection of surgical scars could prevent scar recurrences after cytoreductive surgery and hyperthermic intraperitoneal chemotherapy for colorectal peritoneal metastases and pseudomyxoma peritonei. However, there is no clear evidence for resecting all surgical scars, irrespective of macroscopic suspicion of scar metastases, and scar resection is associated with wound complications. Careful macroscopic assessment of surgical scars is needed to avoid routine scar resection. This study aimed to analyze the correlation between macroscopically suspected and microscopically confirmed scar metastases, and to analyze the prognostic impact of not undergoing routine scar resection. This study showed that occult scar metastases were uncommon and patients not undergoing routine scar resection did not have worse recurrence-free or overall survival compared with those undergoing scar resection. Therefore, macroscopically benign-appearing scars can be left without resection, though resection should be performed in case of uncertainty. Background: Careful macroscopic assessment of surgical scars is needed to avoid routine scar resection during cytoreductive surgery (CRS) for peritoneal metastases (PM). This study aimed to analyze the correlation between macroscopically suspected and microscopically confirmed scar metastases (SMs), and to analyze the prognostic impact of not undergoing routine scar resection. Method: All patients with previous surgery, treated with CRS and hyperthermic intraperitoneal chemotherapy, for colorectal PM or pseudomyxoma peritonei (PMP), at Uppsala University Hospital in 2013–2021, were included. Macroscopic SMs in surgical reports were compared with histopathological analyses. Results: In total, 227 patients were included. Among colorectal PM patients (n = 156), SM was macroscopically suspected in 41 (26%) patients, and 63 (40%) underwent scar resection. SM was confirmed in 19 (30%). Among patients with macroscopic suspicion, 45% had confirmed SM (positive predictive value, PPV). A total of 1 of 23 (4%) patients with no macroscopic suspicion had SM (negative predictive value, NPV = 96%). Among the PMP patients (n = 71), SM was macroscopically suspected in 13 (18%), and 28 (39%) underwent scar resection, of whom 12 (43%) had SM. The PPV was 77%. Occult SM was found in 1 of 14 (NPV = 93%). Not undergoing routine scar resection did not affect recurrence-free survival (RFS, p = 0.2) or overall survival (OS, p = 0.1) in colorectal PM patients or PMP patients (RFS p = 0.7, OS p = 0.7). Conclusion: Occult SM is uncommon and scar resection does not affect RFS or OS. Therefore, macroscopically benign-appearing scars can be left without resection, though resection should be performed upon suspicion or uncertainty. [ABSTRACT FROM AUTHOR]

BackgroundThere is a paucity of targeted therapies for patients with pseudomyxoma peritonei (PMP) secondary to low-grade appendiceal mucinous neoplasms (LAMNs). Dysregulated metabolism has emerged as a hallmark of cancer, and the relationship of metabolomics and cancer is an area of active scientific exploration. We sought to characterize phenotypic differences found in peritoneal metastases (PM) derived from LAMN versus adenocarcinoma.MethodsTumors were washed with phosphate-buffered saline (PBS), microdissected, then dissociated in ice-cold methanol dried and reconstituted in pyridine. Samples were derivatized in tert-butyldimethylsilyl (TBDMS) and subjected to gas chromatography-coupled mass spectrometry. Metabolites were assessed based on a standard library. RNA sequencing was performed, with pathway and network analyses on differentially expressed genes.ResultsEight peritoneal tumor samples were obtained and analyzed: LAMNs (4), and moderate to poorly differentiated adenocarcinoma (colon [1], appendix [3]). Decreases in pyroglutamate, fumarate, and cysteine in PM from LAMNs were found compared with adenocarcinoma. Analyses showed the differential gene expression was dominated by the prevalence of metabolic pathways, particularly lipid metabolism. The gene retinol saturase (RETSAT), downregulated by LAMN, was involved in the multiple metabolic pathways that involve lipids. Using network mapping, we found IL1B signaling to be a potential top-level modulation candidate.ConclusionsDistinct metabolic signatures may exist for PM from LAMN versus adenocarcinoma. A multitude of genes are differentially regulated, many of which are involved in metabolic pathways. Additional research is needed to identify the significance and applicability of targeting metabolic pathways in the potential development of novel therapeutics for these challenging tumors.

Case description: We report here the case of a 64-year-old male presenting pathological fractures of T6 and T7 due to pseudomyxoma peritonei extension to the pleural cavity and thoracic spine. He presented interscapular pain with mild spinal cord compression symptoms. He was treated by achieving T5-T8 laminectomy, T2-T10 pedicle fixation, and T6-T7 vertebrectomy. The postoperative course was uneventful apart from a pulmonary embolism with favorable evolution under anticoagulants. Conclusion: Pseudomyxoma peritonei is a rare condition, with no previously described location in the spine. Here is described the case of a PMP extension to the thorax then the spine, treated with two-level vertebrectomy, laminectomy, and posterior fusion.

Background: Pseudomyxoma peritonei (PMP) is a clinical syndrome characterised by intraperitoneal accumulation of mucus due to mucinous neoplasia. It is a rare condition affecting 1–2 per million individuals per year. The majority of PMP arises from a ruptured mucinous appendiceal tumour, with infrequent occurrences from other primary gastrointestinal tumours and mucinous ovarian tumours. PMP arising from a mature ovarian teratoma is a rare entity, with limited case reports in the literature. Given the infrequent and sporadic occurrences of these tumours, little is known about the tumour behaviour and prognosis. Case series and literature review: Herein, we report six cases of PMP arising from a mature ovarian teratoma who were treated with primary cytoreductive surgery (CRS), with one case of recurrence. Literature review identified 21 cases from 12 manuscripts. Nineteen patients were treated with CRS alone, with two patients receiving adjuvant hyperthermic intraperitoneal chemotherapy (HIPEC). Follow up data were variably reported, with no recurrence in 20 patients during their follow up of 5–54 months. One patient reported to have died of disease at 49 months. Conclusion: Despite the lack of high-quality evidence and limitations of small case series, our review indicates that close surveillance after CRS could be considered as the preferred treatment over more morbid CRS and HIPEC, with HIPEC reserved for patients who recur or progress after CRS.

Introduction: Cytoreductive surgery (CRS) and intraperitoneal chemotherapy (IPC) represent a high-risk for venous thromboembolism (VTE) due to malignancy, prolonged surgery and immobility. We investigated the incidence of and risk factors for VTE following CRS/IPC. Materials and methods: Data was analysed on 130 CRS/IPC performed over a 6-year period at a single centre, the Western Australian Peritonectomy Service (WAPS), on lower gastrointestinal neoplasia: pseudomyxoma peritoneii (PMP), colorectal cancer (CRC) and appendix cancer (AC). Data was analysed by univariate and multivariate logistic regression to identify risk factors for VTE. Results: 31 patients (24 %) experienced a VTE. The percentages of VTE among patients with PMP (n = 50), CRC (n = 53) and AC (n = 27) were 36 %, 17 % and 15 % respectively. 60 % of these cases were asymptomatic. The odds of VTE were higher for PMP patients than in patients with a other histopathology (OR=2.9, p = 0.01). Other significant risk factors for VTE on univariate analysis were PCI (OR=1.07, p = 0.001), pelvic dissection (OR=5.52, p = 0.001) and operation time (OR=1.36, p = 0.001). Conclusion: This study demonstrates high rates of VTE in patients undergoing CRS/IPC. Patients with PMP have a three-fold higher risk of VTE compared to other malignancies (CRC+AC). As most VTE cases were asymptomatic, aggressive early investigation and intervention is indicated for patients undergoing CRS/IPC.

A 52-year old female presenting with an ovarian mass underwent total abdominal hysterectomy and bilateral salpingo-oophorectomy. Intra-operatively there was large volume ascites containing mucin and hair. Subsequent pathological examination of the ovarian mass revealed a low-grade mucinous neoplasm arising within a mature cystic teratoma (MCT). This was associated with pseudomyxoma peritonei (PMP) and is a rare entity recognized by the World Health Organisation. These tumours resemble their appendiceal counterpart and therefore diagnosis is achieved with immunohistochemistry and thorough morphological assessment to exclude a collision tumour. Additionally, the appendix should be examined to confirm ovarian origin. Identification of these neoplasms is crucial as reasonable outcomes can be achieved following appropriate referral for ongoing management which includes complete surgical cytoreduction and hyperthermic intraperitoneal chemotherapy (HIPEC). [ABSTRACT FROM AUTHOR]

Appendiceal mucinous neoplasms, particularly Low-grade Appendiceal Mucinous Neoplasms (LAMN), are rare but important diagnostic entities as they are potential causes of a surgical abdomen. The clinical manifestations of this lesion are obscure and ill-defined, and these lesions are commonly misdiagnosed as acute appendicitis, adnexal masses, or retroperitoneal tumours. This lesion can rupture and seed mucin and neoplastic epithelium into the peritoneum, leading to Pseudomyxoma Peritonei (PMP), a serious complication with a high morbidity and mortality rate. Therefore, timely identification and treatment of LAMN are crucial for reducing the risk of PMP and improving prognosis and outcomes. Ultrasonography (USG) and Computed Tomography (CT) scans are useful methods for diagnosis; however, the diagnosis is often incidental or found intraoperatively during resection for suspected acute appendicitis. Clinical awareness of the misleading presentations of LAMN should be present in cases of a surgical acute abdomen to prevent performing a dissimilar treatment intervention. Considering the rarity of this lesion and its varied presentation, it is important to study and document this type of neoplasia in the literature. Hereby, authors report a rare case of LAMN in a 33-year-old male patient with a primary diagnosis of acute appendicitis. This case highlights the importance of having a high index of clinical suspicion of appendiceal malignancy and mucocele rupture in patients planned for appendectomy. This also emphasises the fact that all excised appendicectomy tissues should be sent for histopathological examination as they can harbor pathological changes like LAMN.

Abstract Background Pseudomyxoma peritonei (PMP) is a rare peritoneal mucinous carcinomatosis with largely unknown underlying molecular mechanisms. Cytoreductive surgery combined with hyperthermic intraperitoneal chemotherapy is the only therapeutic option; however, despite its use, recurrence with a fatal outcome is common. The lack of molecular characterisation of PMP and other mucinous tumours is mainly due to the physicochemical properties of mucin. Results This manuscript describes the first protocol capable of breaking the mucin barrier and isolating proteins from mucinous tumours. Briefly, mucinous tumour samples were homogenised and subjected to liquid chromatography using two specific columns to reduce mainly glycoproteins, albumins and immunoglobulin G. The protein fractions were then subjected to mass spectrometry analysis and the proteomic profile obtained was analysed using various bioinformatic tools. Thus, we present here the first proteome analysed in PMP and identified a distinct mucin isoform profile in soft compared to hard mucin tumour tissues as well as key biological processes/pathways altered in mucinous tumours. Importantly, this protocol also allowed us to identify MUC13 as a potential tumour cell marker in PMP. Conclusions In sum, our results demonstrate that this protein isolation protocol from mucin will have a high impact, allowing the oncology research community to more rapidly advance in the knowledge of PMP and other mucinous neoplasms, as well as develop new and effective therapeutic strategies.

Background The greater omentum is routinely resected during cytoreductive surgery (CRS), but few studies have analyzed the rationale behind this. This study aimed to assess the prevalence of omental metastases (OM) and the correlation between macroscopically suspected and microscopically confirmed OM, in patients with pseudomyxoma peritonei (PMP) or colorectal peritoneal metastases (PM).Method All patients without previous omentectomy, treated with initial CRS and hyperthermic intraperitoneal chemotherapy for PMP or colorectal PM, at Uppsala University Hospital in 2013–2021, were included. Macroscopic OM in surgical reports was compared with histopathological analyses.Results In all, 276 patients were included. In those with PMP, 112 (98%) underwent omentectomy and 67 (59%) had macroscopic suspicion of OM. In 5 (4%) patients, the surgeon was uncertain. Histopathology confirmed OM in 81 (72%). In patients with macroscopic suspicion, 96% had confirmed OM (positive predictive value, PPV). In patients with no suspicion, 24% had occult OM (negative predictive value, NPV = 76%). In patients with colorectal PM, 156 (96%) underwent omentectomy and 97 (60%) had macroscopic suspicion. For 5 (3%) patients, the surgeon was uncertain. OM was microscopically confirmed in 90 (58%). PPV was 85% and NPV was 89%. The presence of OM was a univariate risk factor for death in PMP (HR 3.62, 95%CI 1.08–12.1) and colorectal PM (HR 1.67, 95%CI 1.07–2.60), but not in multivariate analyses.Conclusion OM was common and there was a high risk of missing occult OM in both PMP and colorectal PM. These results support the practice of routine omentectomy during CRS.

Background: Pseudomyxoma peritonei (PMP) is a rare peritoneal mucinous carcinomatosis with largely unknown underlying molecular mechanisms. Cytoreductive surgery combined with hyperthermic intraperitoneal chemotherapy is the only therapeutic option; however, despite its use, recurrence with a fatal outcome is common. The lack of molecular characterisation of PMP and other mucinous tumours is mainly due to the physicochemical properties of mucin. Results: This manuscript describes the first protocol capable of breaking the mucin barrier and isolating proteins from mucinous tumours. Briefly, mucinous tumour samples were homogenised and subjected to liquid chromatography using two specific columns to reduce mainly glycoproteins, albumins and immunoglobulin G. The protein fractions were then subjected to mass spectrometry analysis and the proteomic profile obtained was analysed using various bioinformatic tools. Thus, we present here the first proteome analysed in PMP and identified a distinct mucin isoform profile in soft compared to hard mucin tumour tissues as well as key biological processes/pathways altered in mucinous tumours. Importantly, this protocol also allowed us to identify MUC13 as a potential tumour cell marker in PMP. Conclusions: In sum, our results demonstrate that this protein isolation protocol from mucin will have a high impact, allowing the oncology research community to more rapidly advance in the knowledge of PMP and other mucinous neoplasms, as well as develop new and effective therapeutic strategies. [ABSTRACT FROM AUTHOR]

Pseudomyxoma peritonei is a rare pathological condition characterized by mucinous tumor tissue implants on the peritoneal surface. Although the cause of Pseudomyxoma peritonei has been extensively studied, the prevailing agreement is that it stems from mucinous tumors that occur in the ovaries or appendix. The tumor tissue typically remains localized to the peritoneum and does not exhibit extraperitoneal spread. Patients with Pseudomyxoma peritonei may present with symptoms such as abdominal pain, bloating, loss of appetite, and shortness of breath. Computerized Tomography is commonly used for diagnostic purposes. The treatment of Pseudomyxoma peritonei typically involves surgical evacuation of the tumoral tissue, followed by cytoreduction and Hyperthermic Intraperitoneal Chemotherapy. While effective treatment options are available, some patients may require repeated surgeries over an extended period. This paper reports on a case study of a patient with a history of recurrent Pseudomyxoma peritonei, necessitating multiple surgical interventions over a decade. The paper concludes with a review of the relevant literature. [ABSTRACT FROM AUTHOR]

Simple Summary: Pseudomyxoma peritonei (PMP) is a rare, slow-growing, and poorly understood neoplasm. It is characterized by varying degrees of malignancy and the production of mucinous, gelatinous structures. The development of PMP is typically associated with the rupture of appendiceal mucinous tumors and other gastrointestinal or ovarian mucinous tumors. This present literature review was conducted to better describe the ovarian causes of PMP. The main instances in which PMP can have an ovarian cause include the following: mucinous cystadenoma, mucinous ovarian cancer, colon cancer with ovarian metastasis, malignant transformation of an ovarian primary mature cystic teratoma, appendiceal mucocele with peritoneal dissemination, mucinous borderline tumor developing inside an ovarian teratoma, and the association between a mucinous bilateral ovarian cancer and a colonic tumor. We undertook a literature study to identify and underline the feasible treatments for PMP, since the limited knowledge of this cancerous condition raises the likelihood of delayed diagnosis or progressive deterioration. Background. Pseudomyxoma peritonei (PMP) is a rare, progressive, slowly growing, inadequately understood neoplasm with a 5-year progression-free survival rate of as low as 48%. It is characterized by varying degrees of malignancy and the production of mucinous and gelatinous structures. Typically, the development of pseudomyxoma peritonei is associated with the rupture of appendiceal mucinous tumors and other gastrointestinal or ovarian mucinous tumors. The goal of our literature review was to identify various aspects that characterize the ovarian causes of pseudomyxoma peritonei. Materials and methods. The authors performed an extensive literature search between 1 February 2024 and 2 March 2024 on the following databases: Pubmed, Scopus, Oxford Journals, and Reaxys, and the findings were summarized into seven main clinical and paraclinical situations. Results. According to our research, the main instances in which pseudomyxoma peritonei can be triggered by an ovarian cause are the following: (1) mucinous cystadenoma; (2) mucinous ovarian cancer; (3) colon cancer with ovarian metastasis; (4) malignant transformation of an ovarian primary mature cystic teratoma; (5) appendiceal mucocele with peritoneal dissemination mimicking an ovarian tumor with peritoneal carcinomatosis; (6) mucinous borderline tumor developing inside an ovarian teratoma; and (7) the association between a mucinous bilateral ovarian cancer and a colonic tumor. Conclusions. In our study, we aimed to provide a comprehensive overview of the ovarian causes of pseudomyxoma peritonei, including its epidemiology, imagery characteristics, symptoms, current treatment, and promising future therapies, in the hopes of finding feasible solutions, as a lack of understanding of this mucus-secreting malignant disease increases the risk of delayed diagnosis or uncontrolled deterioration. [ABSTRACT FROM AUTHOR]

Background: Non-carcinoid appendix epithelial tumors are rare. These tumors include low-grade and high-grade mucinous neoplasm also adenocarcinomas. We aimed to investigate the clinicopathological features, treatment, and risk factors of recurrence. Methods: Patients diagnosed between 2008 and 2019 were retrospectively analyzed. Categorical variables were expressed as percentages and compared using the Chi-square test or Fisher’s exact tests. Overall survival and Disease-free survival of the groups were calculated by the Kaplan–Meier method, and the log-rank test was used to compare the survival rates. Results: A total of 35 patients were included in the study. Of the patients, 19 (54%) were women and the median diagnosis age of patients was 50.4 years (19–76). As for pathological types, a total of 14 (40%) patients were mucinous adenocarcinoma and 14 (40%) patients were Low-Grade Mucinous Neoplasm (LGMN). Lymph node excision and lymph node involvement were 23 (65%) and 9 (25%) patients respectively. The majority of patients were stage 4 (27, 79%) and 25 (71%) of these patients had peritoneal metastasis. A total of 48.6% patients had been treated with cytoreductive surgery and hyper-thermic intraperitoneal chemotherapy. Median Peritoneal cancer index value was 12 (2-36). The median follow-up time was 20 (1-142) months. Recurrence developed in 12 (34%) of patients. When risk factors for recurrence are considered, there was a statistically significant difference in appendix tumors with high-grade, adenocarcinoma pathology, ones with peritoneal cancer index ≥12 and not having pseudomyxoma peritonei. Median disease-free survival was 18 (13-22, 95% CI) months. Median overall survival could not be reached while the 3-year survival rate was 79%. Conclusion: The risk of recurrence is higher in high-grade appendix tumors, having peritoneal cancer index ≥ 12, not having pseudomyxoma peritonei and adenocarcinoma pathology. High-grade appendix adenocarcinoma patients should be followed closely for recurrence. [ABSTRACT FROM AUTHOR]

Simple Summary: Pseudomyxoma peritonei (PMP) is a rare disease and has, thus, been the focus of relatively few studies in the field of digestive system research. Even experts and scholars in this field have certain deficiencies in their understanding of the disease. Although the standard treatment of cytoreductive surgery (CRS) combined with hyperthermic intraperitoneal chemotherapy (HIPEC) has improved patient prognosis, problems such as the difficulty of operation, tumor recurrence, single treatment method, and poor quality of life cannot be properly solved. This review mainly examines the progress of biological research and the existing or potential treatment strategies in relation to pseudomyxoma peritonei. It is expected to help scholars in related fields to understand the disease and provide potential directions for research into more effective and personalized treatment strategies. Pseudomyxoma peritonei (PMP) is a rare disease characterized by extensive peritoneal implantation and mass secretion of mucus after primary mucinous tumors of the appendix or other organ ruptures. Cytoreductive surgery (CRS) combined with hyperthermic intraperitoneal chemotherapy (HIPEC) is currently the preferred treatment, with excellent efficacy and safety, and is associated with breakthrough progress in long-term disease control and prolonged survival. However, the high recurrence rate of PMP is the key challenge in its treatment, which limits the clinical application of multiple rounds of CRS-HIPEC and does not benefit from conventional systemic chemotherapy. Therefore, the development of alternative therapies for patients with refractory or relapsing PMP is critical. The literature related to PMP research progress and treatment was searched in the Web of Science, PubMed, and Google Scholar databases, and a literature review was conducted. The overview of the biological research, treatment status, potential therapeutic strategies, current research limitations, and future directions associated with PMP are presented, focuses on CRS-HIPEC therapy and alternative or combination therapy strategies, and emphasizes the clinical transformation prospects of potential therapeutic strategies such as mucolytic agents and targeted therapy. It provides a theoretical reference for the treatment of PMP and the main directions for future research. [ABSTRACT FROM AUTHOR]

Background: Pseudomyxoma peritonei (PMP) is a rare clinical malignant syndrome, and its rarity causes a lack of pathology research. This study aims to quantitatively analyze HE‐stained pathological images (PIs), and develop a new predictive model integrating digital pathological parameters with clinical information. Methods: Ninety‐two PMP patients with complete clinic‐pathological information, were included. QuPath was used for PIs quantitative feature analysis at tissue‐, cell‐, and nucleus‐level. The correlations between overall survival (OS) and general clinicopathological characteristics, and PIs features were analyzed. A nomogram was established based on independent prognostic factors and evaluated. Results: Among the 92 PMP patients, there were 34 (37.0%) females and 58 (63.0%) males, with a median age of 57 (range: 31–76). A total of 449 HE stained images were obtained for QuPath analysis, which extracted 40 pathological parameters at three levels. Kaplan–Meier survival analysis revealed eight clinicopathological characteristics and 20 PIs features significantly associated with OS (p < 0.05). Partial least squares regression was used to screen the multicollinearity features and synthesize four new features. Multivariate survival analysis identified the following five independent prognostic factors: preoperative CA199, completeness of cytoreduction, histopathological type, component one at tissue‐level, and tumor nuclei circularity variance. A nomogram was established with internal validation C‐index 0.795 and calibration plots indicating improved prediction performance. Conclusions: The quantitative analysis of HE‐stained PIs could extract the new prognostic information on PMP. A nomogram established by five independent prognosticators is the first model integrating digital pathological information with clinical data for improved clinical outcome prediction. Pseudomyxoma peritonei (PMP) is a rare clinical malignant syndrome, and its rarity causes the insufficiency of pathology research. This study established a prognosis nomogram prediction model based on new pathological characteristics of PMP through quantitative analysis of pathological images. [ABSTRACT FROM AUTHOR]

Introduction: Mucocoele of the appendix occurs in 0.2-0.7% of people in the world without any well-defined clinical symptoms. It occurs when there is an accumulation of mucous in the lumen of the appendix. Case Presentation: We present three cases: a 48-year-old male admitted to the emergency room with a one-day history of right iliac fossa pain. Abdominal examination was suggestive of acute appendicitis. The initial abdominal computerised tomography scan was reported as being unremarkable. At surgery, a firm tumour of the appendix was found, and a limited right hemicolectomy was done. Histopathology confirmed a mucocoele of the appendix with borderline mucinous histology. The second case is a 63-year-old man who presented with a one-year history of abdominal distension and weight loss. Previous abdominal ultrasound was suggestive of liver cirrhosis with significant ascitic fluid. Abdominal magnetic resonance imaging found an appendix mucocoele with infiltration of the omentum and scalloping of the liver surface suggestive of pseudomyxoma peritonei. A percutaneous biopsy of the omental mass confirmed metastatic mucinous adenocarcinoma of the appendix. The third case is a 68-year-old man who, during an annual medical check-up, had an incidental finding of a cystic right iliac fossa mass on ultrasound, confirmed on abdominopelvic computerised tomography scan to be an appendix mucocele. He had laparoscopic appendicectomy. The histopathological diagnosis confirmed a mucinous cystadenoma of the appendix. Conclusion: Preoperative diagnosis of appendiceal mucocoele is difficult and commonly discovered intraoperatively. The prognosis is good for the histologically benign type, but it is poor when malignant or peritoneal lesions are present. [ABSTRACT FROM AUTHOR]

Pseudomyxoma peritonei (PMP) is a rare phenomenon, characterized by accumulation of mucus in the abdominal cavity due to a mucinous neoplasm. Histologically, PMP is divided into three prognostic classes, namely low-grade mucinous carcinoma peritonei (LGMCP), high-grade mucinous carcinoma peritonei (HGMCP), and high-grade mucinous carcinoma peritonei with signet ring cells (HGMCP-S); HGMCP-S exhibits the worst prognosis. Complete cytoreductive surgery and hyperthermic intraperitoneal chemotherapy have been established as the standard therapy for PMP. However, 50% of patients with PMP experience a recurrence, and 30–40% are unable to receive the standard treatment due to invasive diseases. Therefore, novel therapies are required for their treatment. Although patient-derived cell lines are important tools for basic and pre-clinical research, PMP cell lines derived from patients with HGMCP-S have never been reported. Thus, we established a novel PMP cell line NCC-PMP2-C1, using surgically resected tumor tissue from a patient with HGMCP-S. NCC-PMP2-C1 cells were maintained for more than five months and passaged 30 times under culture conditions. NCC-PMP2-C1 cells exhibited multiple deletions and somatic mutations, slow growth, histological features, and dissemination of tumor cells in nude mice. Screening for the anti-proliferative effects of anti-cancer drugs on cells revealed that bortezomib, mubritinib, and romidepsin had a significant response against NCC-PMP2-C1 cells. Thus, the NCC-PMP2-C1 cell line is the first PMP cell line harboring signet ring cells and will be a valuable resource for basic and preclinical studies of HGMCP-S. [ABSTRACT FROM AUTHOR]