Pseudomyxoma Peritonei of Extra-Appendiceal Origin: A Comparative Study

Pseudomyxoma peritonei arising from mature ovarian teratoma, a rare entity: Report of six cases and review of current literature

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.

Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy to Treat Pseudomyxoma Peritonei of Ovarian Origin: A Retrospective French RENAPE Group Study

BACKGROUND

Ovarian pseudomyxoma peritonei (OPMP) are rare, without well-defined therapeutic guidelines. We aimed to evaluate cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) to treat OPMP.

METHODS

Patients from the French National Network for Rare Peritoneal Tumors (RENAPE) database with proven OPMP treated by CRS/HIPEC and with histologically normal appendix and digestive endoscopy were retrospectively included. Clinical and follow-up data were collected. Histopathological and immunohistochemical features were reviewed.

RESULTS

Fifteen patients with a median age of 56 years were included. The median Peritoneal Cancer Index was 16. Following CRS, the completeness of cytoreduction (CC) score was CC-0 for 9/15 (60%) patients, CC-1 for 5/15 (33.3%) patients, and CC-2 for 1/15 (6.7%) patients. The median tumor size was 22.5 cm. After pathological review and immunohistochemical studies, tumors were classified as Group 1 (mucinous ovarian epithelial neoplasms) in 3/15 (20%) patients; Group 2 (mucinous neoplasm in ovarian teratoma) in 4/15 (26.7%) patients; Group 3 (mucinous neoplasm probably arising in ovarian teratoma) in 5/15 (33.3%) patients; and Group 4 (non-specific group) in 3/15 (20%) patients. Peritoneal lesions were OPMP pM1a/acellular, pM1b/grade 1 (hypocellular) and pM1b/grade 3 (signet-ring cells) in 13/15 (86.7%), 1/15 (6.7%) and 1/15 (6.7%) patients, respectively. Disease-free survival analysis showed a difference (p = 0.0463) between OPMP with teratoma/likely-teratoma origin (groups 2 and 3; 100% at 1, 5, and 10 years), and other groups (groups 1 and 4; 100%, 66.6%, and 50% at 1, 5, and 10 years, respectively).

CONCLUSION

These results suggested that a primary therapeutic strategy using complete CRS/HIPEC for patients with OPMP led to favorable long-term outcomes.

Global trends in research of pseudomyxoma peritonei: a bibliometric and visualization analysis

Objective

Pseudomyxoma peritonei (PMP) was a complex disease that had attracted increasing attention. However, there had been no bibliometric analysis of this disease so far. This study aimed to explore the current situation and frontier trend of PMP through bibliometric and visualization analysis, and to indicate new directions for future research.

Methods

The original research articles and reviews related to the PMP research were downloaded from Web of Science Core Collection on September 11, 2023. CiteSpace (6.2.R4) and VOSviewer(1.6.18) were used to perform bibliometric analysis of the publications, and establish the knowledge map. The data collected was analyzed using the Online Analysis Platform of Bibliometric to evaluate the cooperation of countries in this field.

Results

We identified 1449 original articles and reviews on PMP published between 1998 and 2023. The number of publications on PMP increased continuously. The United States, the United Kingdom and China were the top contributors. The most productive organization was the MedStar Washington Hospital Center. Sugarbaker, Paul H. was the most prolific author and the most cited. Keyword analysis showed that "Pseudomyxoma peritonei", "cancer", "cytoreductive surgery", and "hyperthermic intraperitoneal chemotherapy" were the most common keywords. The earliest and latest used keywords were "mucinous tumors" and "impact", respectively. "classification", "cytoreductive surgery", "appendiceal" were the top 3 strongest citation bursts. The reference "Carr NJ, 2016, AM J SURG PATHOL" had the highest co-citations.

Conclusion

This bibliometric analysis showed an increasing trend in literature related to PMP. The research trends and hotspots identified in this study could guide the future research directions in this field, in order to promote the development of PMP.

Ultrasound-guided day-case wide-bore percutaneous mucin aspiration in advanced pseudomyxoma peritonei

AIM

To evaluate percutaneous ultrasound-guided day-case mucin aspiration in advanced pseudomyxoma peritonei (PMP) using a wide-bore drain with regards to its safety and efficacy.

MATERIALS AND METHODS

All patients who underwent percutaneous mucin aspiration for PMP between 2019-2021 at a single national peritoneal tumour service were included in this study. Under local anaesthesia, a suction-enabled 28-32 F catheter was used for drainage following wire-guided track dilatation. The volume drained and difference in abdominal girth pre- and post-procedure were measured. Patients graded difficulty in breathing and abdominal discomfort pre- and post-procedure. Histology reports were reviewed.

RESULTS

Sixteen patients received 56 percutaneous mucin aspirations between 2019-2021. The aetiology was a low-grade appendiceal mucinous neoplasm (LAMN) in 50% of patients. The mean amount of mucin drained was 7,320 ± 3,000ml (range 300-13,500 ml). The mean reduction in abdominal girth post-procedure was 12.2 ± 5 cm (range 0-27 cm). Only grade 1 complications were observed.

CONCLUSION

Percutaneous ultrasound-guided day-case aspiration of mucin for advanced and recurrent PMP using a wide-bore drain is a safe and effective procedure. It may be used in the palliative setting or as a bridge to surgery in the very symptomatic patient or if there is a reversible contraindication to surgery.

Relapse of Pseudomyxoma Peritonei After Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy: Pattern of Failure, Clinical Management and Outcomes

INTRODUCTION

Cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS/HIPEC) have dramatically improved pseudomyxoma peritonei (PMP) prognosis, but treatment failures are still a concern. We investigated the pattern of failure, treatment and outcomes of progressing disease.

METHODS

A prospective database of 374 PMP patients was reviewed, and 152 patients relapsing after complete CRS/HIPEC were identified. PMP was graded according to the Peritoneal Surface Oncology Group International (PSOGI) classification. Hematogenous metastases and non-regional lymph node involvement were considered as systemic metastases.

RESULTS

Median follow-up was 78.3 months (95% confidence interval [CI] 66.7-90.4). PMP relapse involved the peritoneum in 112 patients, pleural cavity in 8, both peritoneum and pleura in 8, systemic sites in 11, and both peritoneum and systemic sites in 13 patients. Systemic metastases involved the lung (n = 14), liver (n = 4), distant nodes (n = 3), bone (n = 2), and both lung and distant nodes (n = 1). Survival after diagnosis of PMP relapse was independently associated with curative versus palliative treatment (hazard ratio [HR] 0.52, 95% CI 0.36-0.75; p = 0.001) and PSOGI histology (HR 1.80, 95% CI 1.19-2.74; p = 0.005), but was not influenced by site of failure (p = 0.444). Ten-year overall survival was 77.5% for 62 patients who had curative-intent surgery for PMP relapse, compared with 83.0% for 192 patients who had no recurrences (p = 0.154) and 26.1% for 90 patients who underwent palliative treatments (p = 0.001).

CONCLUSIONS

Relapse after CRS/HIPEC most commonly involves the peritoneum, but pleural recurrences and systemic metastases occur in a small but clinically relevant number of patients. In selected patients, surgical resection of recurrent disease can result in long survival, irrespective of sites of failure.

[CT Findings of Mucinous Adenocarcinoma Arising from the Renal Calyx in Horseshoe Kidney: A Case Report]

Mucinous adenocarcinoma of the kidney is an extremely rare cystic malignant tumor with a poor prognosis that occurs in the pelvicalyceal system. Pre-opeartive diagnosis is very difficult because the tumor's clinical and imaging features are nonspecific. Here we report a case of primary mucinous adenocarcinoma arising from the horseshoe kidney in a 69-year-old male, focusing on CT findings. The tumor was a complex cystic mass with irregular wall thickening, multifocal calcifications, and septa and progressed to pseudomyxoma peritonei postoperatively.

Prevalence and incidence of pseudomyxoma peritonei in urban China: A nationwide retrospective cohort study

BACKGROUND

Pseudomyxoma peritonei (PMP) is an extremely rare condition. Information regarding the disease burden of PMP in developing countries is limited. This study aimed to determine the epidemiology of PMP in China.

METHODS

PMP data were extracted from the national databases of Urban Basic Medical Insurance. All cases were identified using the International Classification of Diseases (ICD) codes and Chinese diagnostic terms. The national prevalence from 2012 to 2016 and incidence in 2016 were estimated.

RESULTS

In total, 153 patients with PMP were identified. The crude prevalence of PMP in 2016 was 2.47 (95% confidence interval [CI] 1.71 to 3.23) per million person-year, with a higher prevalence in females than males. Prevalence increased with age, with the first peak in those aged 15-29 years and the highest in those aged >80 years. The crude incidence of PMP in 2016 was 1.19 (95% CI 0.59 to 1.78) per million person-years. Similar to the prevalence, the rates were higher in women than in men. The incidence also increased with age, with the highest prevalence in those aged >80 years. Besides, the most frequent comorbidities before and after the first diagnosis of PMP were unspecified secondary malignancies and malignancies of unspecified sites, followed by abdominal malignant tumours.

CONCLUSIONS

The rate of PMP was lower in mainland China than in European countries and increased with advancing age. Women were more likely to have PMP than men. Furthermore, an insufficient understanding of this rare disease presents a major challenge in accurately evaluating the disease burden.

Prognosis for Young Females with Pseudomyxoma Peritonei of Appendiceal Origin and Unilateral or Bilateral Ovaries Preserved During Cytoreductive Surgery

Objective

To determine prognosis for young female patients with peritoneal pseudomyxoma (PMP) of appendiceal origin and unilateral or bilateral ovaries preserved during cytoreductive surgery (CRS).

Methods

Clinical data of female patients treated with CRS with or without hyperthermic intraperitoneal chemotherapy (HIPEC) at the Aerospace Center Hospital, Beijing between January, 2009 and December, 2019 were retrospectively reviewed. Patients had no changes in the bilateral ovaries on gross pathological observations or biopsy during CRS, and normal ovarian function. The demographic and clinical characteristics and prognosis of women with ovaries preserved (ovarian preservation group) or resected (ovarian resection group) during CRS were compared. Independent prognostic factors for survival were identified using univariate and multivariate analysis.

Results

40 patients were included in the final analysis. 19 patients chose ovarian preservation while 21 patients underwent ovarian resection. Completeness of cytoreduction (CCR) scores were CCR-0/1. There were significant differences in age (<40 vs. ≥40), symptoms, intraoperative HIPEC (Y vs. N), and histopathologic subtype of PMP (low-grade vs. high-grade) (p < 0.001) between patients in the ovarian preservation and ovarian resection groups. In the ovarian preservation group, median overall survival (OS) was 59 months (range, 53–65 months), and the 5-year survival rate was 37.9%. Median disease-free survival (DFS) was 13 months (range, 9–17 months), and the 5-year recurrence rate was 87.4%. In the ovarian resection group, the 5-year survival rate was 87.7%, and the 5-year recurrence rate was 18.3%. Median OS and median DFS were not reached. In patients with low-grade PMP, median DFS was significantly longer in patients with ovarian resection compared to ovarian preservation (p < 0.001). Univariate analysis showed histopathologic subtype of PMP (low-grade vs. high-grade, p < 0.001) was significantly associated with OS and DFS. On multivariate analysis, high-grade histopathologic subtype of PMP was an independent predictor of poor prognosis (OS and DFS).

Conclusion

Histopathologic subtype of PMP represents an independent predictor of prognosis in female patients with PMP of appendiceal origin and unilateral or bilateral ovaries preserved during CRS. These findings imply that ovarian preservation is a more suitable option for young females with low-grade PMP compared to high-grade PMP. Further prospective studies should be done investigating the role of resection of uninvolved ovaries in PMP.

A case of Pseudomyxoma Peritonei of an unexpected origin

Background

Pseudomyxoma peritonei (PMP) is a complex and partially understood disease defined by mucin deposits in the peritoneal cavity, mostly of appendiceal origin caused by the rupture of a mucocele often containing Low or High grade Appendiceal Mucinous Neoplasm (LAMN/HAMN). Other origins include primitive ovarian mucinous cystadenoma or cystadenocarcinoma almost always with an associated teratoma, but to our knowledge no case of ovarian teratomatous appendiceal-like mucocele with LAMN has been reported as a cause of PMP.

Case presentation

A 25-year old female with infertility was diagnosed with an isolated left ovarian tumor in a context of PMP. Histological examination revealed an ovarian teratoma containing an appendiceal-like structure with mucocele and LAMN, without any associated lesion of the appendix on full histological analysis. Molecular characterization of the ovarian lesion showed co-KRAS and GNAS mutations, as described in PMP of appendiceal origin, while only KRAS mutations are reported in primitive ovarian mucinous tumor.

Conclusions

Detection of co-KRAS and GNAS mutations in our case of ovarian teratomatous appendiceal-like mucocele with LAMN shows that when PMP derives from a mucinous ovarian lesion (with histological proof of none-appendiceal involvement), it is probably of a digestive teratomatous origin, emphasizing the need to actively search for tetatomatous signs in a context of ovarian PMP.

Pseudomyxoma peritonei originating from intestinal duplication: A case report and review of the literature

BACKGROUND

Pseudomyxoma peritonei (PMP) is a rare mucinous neoplasm with a relatively low incidence of 1 to 2 per million individuals. It is typically characterized by a type of gelatinous ascites named “jelly belly”. Most cases of PMP occur in association with ruptured primary mucinous tumors of the appendix (90%). Periodically, PMP can originate from mucinous carcinomas at other sites, including the colorectum, gallbladder, and pancreas. However, unusual origin can occur, as noted in this case report.

CASE SUMMARY

A 52-year-old woman had an unusual derivation of PMP from intestinal duplication. The patient complained of abdominal distension and increasing abdominal girth. Abdominal contrast-enhanced computed tomography showed a mass in the greater omentum located on the left side of the abdomen, likely to be a cystic mass of peritoneal origin. A PMP diagnosis was presumed based on the specific signs of the mass with flocculent and stripe-like echoes in ultrasound images. Ultrasound-guided percutaneous aspiration suggested a high likelihood of PMP. Once the PMP diagnosis was recognized, identification of the origin of the primary tumor was indicated. Thus, an exploratory laparoscopy was performed. In the absence of a primary tumor of appendix origin, the diagnosis of a low-grade mucinous neoplasm of intestinal duplication origin was finally confirmed by histopathology.

CONCLUSION

PMP is secondary to mucinous carcinomas of the appendix mostly. This case resulted from an unusual derivation from intestinal duplication.

Rare primary peritoneal mucinous adenocarcinoma in a 69-year-old man

Primary peritoneal mucinous adenocarcinoma is rare in men. The low-grade tumor consisted of mucin-producing columnar cells with minimal nuclear atypia. Relationship to pseudomyxoma peritonei and disseminated peritoneal adenomucinosis is discussed.

Clinicopathological Characteristics and Prognostic Prediction in Pseudomyxoma Peritonei Originating From Mucinous Ovarian Cancer

Objective

To describe the clinicopathological characteristics of mucinous ovarian cancer (MOC)-derived pseudomyxoma peritonei (PMP) and identify prognostic factors for survival.

Methods

Medical records from patients with MOC-derived PMP who attended the Aerospace Center Hospital, Beijing, China between January 2009, and December 2019 were retrospectively reviewed. Survival analysis was performed with the Kaplan-Meier method, the log-rank test, and a Cox proportional hazards model.

Results

Cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) for PMP originating from MOC were performed on 22 patients, who had a median age of 52 years at the time of surgery. At the last follow-up in June 2020, 9 (41%) patients were still alive. Median OS was 12 months (range, 1 to 102 months), and the 2-, 3-, and 5-year survival rates were 23, 9, and 5%, respectively.

Conclusion

Histopathologic subtype and PCI may be applied as predictors of prognosis in patients with MOC-derived PMP. Patients with high-grade disease could benefit from completeness of cytoreduction (CCR) 0/1.

Evaluation of the significance of pseudomyxoma peritonei patients based on the Peritoneal Surface Oncology Group International (PSOGI) classification

BACKGROUND

Pseudomyxoma peritonei (PMP) is a rare disease characterized by mucinous ascites and deposits on the peritoneal surfaces. The study aimed to assess PMP patients according to the Peritoneal Surface Oncology Group International (PSOGI) classification, as a part of standardization of this rare disease.

METHODS

This retrospective study analyzed PMP patients who underwent surgery between January 2007 and December 2017. All histologic slides were re-evaluated and the clinical data were collected. According to the PSOGI, PMP was retrospectively classified into three categories: low-grade (LG-PMP), high-grade (HG-PMP), and signet-ring cells (SRC-PMP). The extent of peritoneal involvement was quantified by the peritoneal cancer index (PCI). The completeness of cytoreduction (CCR) was dichotomized as complete or incomplete.

RESULTS

Fifty-seven patients were included in this study, consisted of 39 patients with LG-PMP (74.0%), 14 with HG-PMP (20.8%), and 4 with SRC-PMP (5.2%). There was no operative mortality and major complications occurred in 24 patients (31.2%). The 5-year overall survival was 56.2% ± 8.1% for LG-PMP, 37.5% ± 12.1% for HG-PMP, and 25.0% ± 21.7% for SRC-PMP. Concerning CCR, the 5-year overall (complete: 59.5% ± 8.4% vs. incomplete: 12.7% ± 8.1%, p = 0.001) and disease-free survival (complete: 38.6% ± 8.9% vs. incomplete: 7.7% ± 6.8%, p = 0.001) were significantly different. In a multivariable analysis, PSOGI classification and CCR independently correlated with survival (p = 0.011 and 0.018, respectively).

CONCLUSIONS

The PSOGI classification provides prognostic stratification, hopefully requiring further validation including every single case of PMP established as a standard criteria.

The Prognostic Impact of Pathology on Patients With Pseudomyxoma Peritonei Undergoing Debulking Surgery: A Systematic Review and Meta-Analysis of Retrospective Studies

Background: Pseudomyxoma peritonei (PMP) is a rare clinical condition with fatal outcomes, which is characterized by the progressive accumulation of mucinous ascites and peritoneal implants. Some studies have reported the effect of PMP biology on patient outcome. The objective of this study was to analyze published articles focusing on the impact of pathology on the prognosis of PMP patients undergoing debulking.

Methods: Data from all studies regarding the prognosis of patients, with different pathologies, who underwent debulking surgery were analyzed. We searched PubMed, the Wiley Online Library, Ovid, and the Cochrane Library (through January 2020). Studies were confined to those articles written in English. Five studies were identified, and the differences in 5-year survival rates were analyzed according to the Kaplan–Meier survival curves. The hazard ratios (HRs) of the 5-year survival rates were calculated.

Results: The mean and median 5-year survival rates of all patients were 39 and 40%, respectively. The median overall survival was 49.3 months. The mean 5-year survival rates of low-grade PMP was 45.2%. The five studies had sufficient data to calculate HRs from the 5-year survival rates data, and three had HRs lower than 1. The total HRs was 0.54, with a 95% CI between 0.33 and 0.89 (P = 0.01).

Conclusions: Among PMP patients receiving debulking surgery who are not able to undergo complete cytoreductive surgery, low-grade biological PMP had a better prognosis than high-grade PMP.

Comparative study of mucinous and non-mucinous appendiceal neoplasms with peritoneal dissemination treated by cyoreductive surgery and hyperthermic intraperitoneal chemotherapy (HIPEC)

BACKGROUND

Appendiceal non-mucinous neoplasms (AnMN) are rare and poorly understood malignancies with no standard treatment. Cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS/HIPEC) is largely used to treat peritoneal disseminations from appendiceal mucinous neoplasms (AMN), but its role with AnMN is unclear.

METHODS

A prospective database of 315 patients with advanced appendiceal primaries undergoing CRS/HIPEC during 1996-2020 was reviewed. Baseline characteristics, operative and long-term outcomes of AnMN were compared with those of AMN. AMN were categorized according to PSOGI classification into high-grade, low-grade, and acellular mucin (AC), based on peritoneal disease histology.

RESULTS

Twenty-three patients (7.3%) with goblet cell carcinoma (GCC; n = 9), intestinal-type adenocarcinoma (ITAC; n = 12), and mixed adeno-neuroendocrine carcinoma (MANEC; n = 2) were identified. AnMN patients were more likely to be males (P = 0.006), have preoperative systemic chemotherapy (P = 0.001), grossly incomplete CRS (P = 0.001), and nodal metastases (P = 0.001), but not systemic relapse after CRS/HIPEC (P = 0.133). Median follow-up was 25.1 months (range 0.8-77.3) for AnMN, and 80.9 months (range 0.1-279.2) for AMN. Median overall survival was 24.0 months for AnMN, 66.2 months for high-grade AMN (P = 0.015), 160.0 months for low-grade ANM (P = 0.001), and not reached for AC (P = 0.001). Among AnMN patients, median survival was 23.4 months for GCC, 38.7 months for ITAC, 20.3 months for MANEC (P = 0.855). In the overall series, histological subtype (P = 0.001), incomplete cytoreduction (P = 0.001), and positive lymph-nodes (P = 0.003) correlated with poorer survival at multivariate analysis.

CONCLUSIONS

AnMN share with AMN a predominant local-regional dissemination pattern, but prognosis after CRS/HIPEC is worse. This strategy needs to be carefully considered for AnMN.

PATIENTS

Development and validation of prognostic nomograms for pseudomyxoma peritonei patients after surgery: A population-based study

BACKGROUND

The aim of study was to develop and validate nomograms for predicting overall survival (OS) and cancer-specific survival (CSS) of patients with pseudomyxoma peritonei (PMP) and compare the predictive accuracy with the American Joint Committee on Cancer (AJCC) staging system.

METHODS

Data of 4959 PMP patients who underwent surgical resection were collected between 2004 and 2015 from the Surveillance Epidemiology and End Results (SEER) database. All included patients were divided into training (n = 3307) and validation (n = 1652) cohorts. The Kaplan-Meier method and Cox proportional hazard model were applied. Nomograms were validated by discrimination and calibration. Finally, concordance index (C-index) was used to compare the predictive performance of nomograms with that of the AJCC staging system.

RESULTS

According to the univariate and multivariate analyses of training sets, both nomograms for predicting OS and CSS combining age, grade, location, N stage, M stage, and chemotherapy were identified. Nomograms predicting OS also incorporated T stage and the number of lymph nodes removed (LNR). The calibration curves showed good consistency between predicted and actual observed survival. Moreover, C-index values demonstrated that the nomograms predicting both OS and CSS were superior to the AJCC staging system in both cohorts.

CONCLUSION

We successfully developed and validated prognostic nomograms for predicting OS and CSS in PMP patients. Two nomograms were more accurate and applicable than the AJCC staging system for predicting patient survival, which may help clinicians stratify patients into different risk groups, tailor individualized treatment, and accurately predict patient survival in PMP.

Pseudomyxoma extraperitonei in horseshoe kidney masquerading as renal hilar tumor: a case report

Pseudomyxoma peritonei, a rare condition consisting of intraperitoneal mucinous tumors and ascites, most commonly arises from mucinous tumors of the appendix. Very rarely, mucinous deposits arise in the retroperitoneum without intraperitoneal involvement. This has been termed pseudomyxoma extraperitonei. It is a rare and poorly understood condition that is heterogeneous in its clinical behavior, and only a few cases presenting as localized disease in the retroperitoneum have been reported. In this paper, we report the first case of pseudomyxoma extraperitonei presenting as a simple renal hilar mass and mimicking a tumor of renal origin in a horseshoe-kidney patient. The patient underwent isthmusectomy and nephrectomy. Immunohistochemical staining suggested appendiceal origin. She remained alive without adjuvant therapy postoperatively, and no evidence of recurrence was present for 25 months.

Pseudomyxoma peritonei: natural history and treatment

Pseudomyxoma peritonei (PMP) is an uncommon disease characterised by mucinous ascites, classically originating from a ruptured low grade mucinous neoplasm of the appendix. The natural history of PMP revolves around the "redistribution phenomenon", whereby mucinous tumour cells accumulate at specific sites with relative sparing of the motile small bowel and to a lesser extent other parts of the gastrointestinal tract. Peritoneal tumour accumulates due to gravity and at the sites of peritoneal fluid absorption, namely, the greater and lesser omentum and the under-surface of the diaphragm, particularly on the right. The optimal treatment is complete macroscopic tumour excision termed cytoreductive surgery (CRS) combined with Hyperthermic Intra-Peritoneal Chemotherapy (HIPEC). Total operating time for complete CRS and HIPEC for extensive PMP is around 10 h and generally involves bilateral parietal and diaphragmatic peritonectomies, right hemicolectomy, radical greater omentectomy with splenectomy, cholecystectomy and liver capsulectomy, a pelvic peritonectomy with, or without, rectosigmoid resection and bilateral salpingo-oophorectomy with hysterectomy in females. A unique feature of low grade PMP, which differs from other peritoneal malignancies, includes slow disease progression, which may be asymptomatic until advanced stages. Additionally, very extensive disease with a high "PCI" (Peritoneal Carcinomatosis Index) may still be amenable to complete excision and cure. In cases where complete tumour removal is not feasible, maximum tumour debulking can still result in long-term survival in PMP. PMP is challenging, complex but nevertheless the most rewarding peritoneal malignancy amenable to cure by CRS and HIPEC.

Cytoreductive surgery and hyperthermic intraperitoneal chemotherapy for pseudomyxoma peritonei of appendicular and extra-appendicular origin

BACKGROUND

The prognostic value of the primary neoplasm responsible for pseudomyxoma peritonei (PMP) remains poorly studied. The aim of this study was to determine the prognosis for patients with extra-appendicular PMP (EA-PMP) treated optimally with complete cytoreductive surgery (CCRS) and hyperthermic intraperitoneal chemotherapy (HIPEC).

METHODS

All patients treated for PMP with CCRS and HIPEC between 1994 and 2016 were selected retrospectively from a French multicentre database. Patients with EA-PMP had pathologically confirmed non-neoplastic appendices and were matched in a 1 : 4 ratio with patients treated for appendicular PMP (A-PMP), based on a propensity score.

RESULTS

Some 726 patients were identified, of which 61 (EA-PMP group) were matched with 244 patients (A-PMP group). The origins of primary tumours in the EA-PMP group included the ovary (45 patients), colon (4), urachus (4), small bowel (1), pancreas (1) and unknown (6). The median peritoneal carcinomatosis index was comparable in EA-PMP and A-PMP groups (15·5 versus 18 respectively; P = 0·315). In-hospital mortality (3 versus 2·9 per cent; P = 1·000) and major morbidity 26 versus 25·0 per cent; P = 0·869) were also similar between the two groups. Median follow-up was 66·9 months. The 5-year overall survival rate was 87·8 (95 per cent c.i. 83·2 to 92·5) per cent in the A-PMP group and 87 (77 to 96) per cent in the EA-PMP group. The 5-year disease-free survival rate was 66·0 (58·7 to 73·4) per cent and 70 (53 to 83) per cent respectively.

CONCLUSION

Overall and disease-free survival following treatment with CCRS and HIPEC is similar in patients with pseudomyxoma peritonei of appendicular or extra-appendicular origin.

Prediction of Resectability in Pseudomyxoma Peritonei with a New CT Score

BACKGROUND

Curative treatment of pseudomyxoma peritonei (PMP) is complete cytoreductive surgery (CRS) with hyperthermic intraperitoneal chemotherapy (HIPEC).

OBJECTIVE

The aim of this study was to build and evaluate a preoperative imaging score to predict resectability.

PATIENTS AND METHODS

Between 2007 and 2014, all PMP patients in two tertiary reference centers who underwent laparotomy with intent to undergo CRS and HIPEC were included in this study retrospectively. Thickness of tumor burden was measured on preoperative multidetector-row computed tomography (MDCT) by two radiologists blinded to surgical results in five predetermined areas. Patients were divided into two cohorts with the same resectability rate (building and validation). The performances of the scores were assessed using receiver operating characteristic (ROC) curve analyses.

RESULTS

Overall, 126 patients were included, with compete CRS being achieved in 91/126 patients (72.2%). Two cohorts of 63 patients matched by age, sex, burden of disease, resectability rate, and pathological grade were constituted. The MDCT score was the sum of the five measures, and was higher in unresectable disease [median 46.2 mm (range 27.9-74.6) vs. 0.0 mm (range 0.0-14.0), p < 0.001]. Area under the ROC curve was 0.863 (range 0.727-0.968) and 0.801 (range 0.676-0.914) in the building and validation cohorts, respectively. A threshold of 28 mm yielded a sensitivity, specificity, positive predictive and negative predictive value of 94, 81, 81 and 94% in the building cohort, and 80, 68, 59 and 85% in the validation cohort, respectively. Using our score, overall and disease-free survival were increased in the group classified as resectable.

CONCLUSION

A simple preoperative MDCT score measuring tumor burden in the perihepatic region is able to predict resectability and survival of PMP patients.

Validation of the Recent PSOGI Pathological Classification of Pseudomyxoma Peritonei in a Single-Center Series of 265 Patients Treated by Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy

BACKGROUND

Controversies still persist regarding the terminology and pathologic classification of appendiceal mucinous neoplasms and associated pseudomyxoma peritonei (PMP). We assessed reproducibility and prognostic significance of the classification recently proposed by the Peritoneal Surface Oncology Group International (PSOGI).

METHODS

A prospective database of 265 PMP patients uniformly treated by cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS/HIPEC) from 1995 to 2017 was reviewed. According to the PSOGI, peritoneal disease was retrospectively classified into three categories: low-grade (LG-PMP), high-grade (HG-PMP), and signet-ring cells (SRC-PMP). Acellular mucin (AC) was classified separately. The extent of peritoneal involvement was quantified by the peritoneal cancer index (PCI).

RESULTS

Twenty-six patients were diagnosed with AC (9.8%), 197 with LG-PMP (74.4%), 38 with HG-PMP (14.3%), and 4 with SRC-PMP (1.5%). In the overall series, median follow-up was 65.5 months (95% confidence interval 53.7-78.8) and 10-year overall survival was 62.9% (median 148.7 months). Operative death occurred in 10 patients (3.8%) and major complications occurred in 89 patients (33.6%). Ten-year survival was 89.6% for AC, 63.2% for LG-PMP, 40.1% for HG-PMP, and 0 for SRC-PMP. In a multivariate model, the World Health Organization (WHO) pathological classification independently correlated with survival (p = 0.028). In a separate model, the PSOGI classification did not reach statistical significance (p = 0.149). Completeness of cytoreduction and PCI > 22 correlated with prognosis in both models.

CONCLUSIONS

AC and SRC-PMP pathological categories of the PSOGI classification identified two subsets of patients with favorable and exceedingly dismal prognosis, respectively. It remains unclear whether the PSOGI classification might provide better prognostic stratification than the current WHO classification. Further studies in larger prospective series are needed.

An unusual case of pseudomyxoma peritonei associated with synchronous primary mucinous tumors of the ovary and appendix: A case report

Pseudomyxoma peritonei (PMP) is a rare disease that usually originates from mucinous neoplasms of the appendix and, less commonly, from extra-appendiceal tumors, but it may also be caused by synchronous primary mucinous tumors of the ovary and appendix. The current study discusses the case of a 73-year-old female who presented with progressively worsening indigestion and abdominal distension. Magnetic resonance imaging of the pelvis revealed a large cystic mass with a thin enhancing septa arising from the right ovary and ascites with scalloping of the liver surface. On laparotomy, the patient was observed to have a large ruptured mass on the right ovary and a partially amputed distended appendix filled with mucin. The subsequent pathology report confirmed a borderline mucinous tumor of the right ovary and a low-grade appendiceal mucinous neoplasm associated with PMP. Immunohistochemical examination demonstrated the ovarian tumor stained strongly positive for cytokeratin (CK)-7, and negatively for CK-20 and homeobox protein CDX-2 (CDX2), whereas the appendiceal tumor stained negative for CK-7 and positive for CK-20 and CDX2. This study presents a rare case of PMP caused by synchronous primary mucinous tumors of the ovary and appendix in a postmenopausal female.