Multicystic peritoneal mesothelioma: outcomes and patho-biological features in a multi-institutional series treated by cytoreductive surgery and Hyperthermic Intraperitoneal Chemotherapy (HIPEC)

Large and Extensive Multilocular Peritoneal Inclusion Cysts Lack Genomic Alterations and Follow an Indolent Clinical Course Despite Rare Recurrences

Peritoneal inclusion cysts (PICs) are unilocular or multilocular cystic lesions lined by bland mesothelial cells. While most are small and localized, rare examples may be large or multifocal with diffuse peritoneal involvement, causing clinical and even pathologic concern for malignancy. We examined 20 PIC, including 8 large solitary and 12 multifocal lesions. Solitary PIC were found in 7 female and 1 male patients ranging from 19 to 55 (median: 37) years. Expanded collagenous (n=2) or edematous (n=1) areas were occasionally seen in the septae, and 1 had microscopic foci of myxoid stroma. Four had hobnail cells, and 1 had minor areas of papillary mesothelial hyperplasia. Multifocal PICs occurred in 9 female and 3 male patients ranging from 26 to 80 (median: 53) years. Three showed extensive associated fibrosis with entrapment of preexisting adipose tissue, 2 had areas resembling granulation tissue, and 3 had scattered foci of myxoid stroma. Hobnail cells were present in 9, papillary mesothelial hyperplasia in 2, entrapped single cells in 1, and 2 had areas resembling adenomatoid tumors. Two of the multifocal PICs had limited local recurrences at 18 and 21 months. No patients died of disease. Clonal alterations were not identified in any of the tested PICs (mutational and fusion analysis in 5, chromosomal microarray in 1). Despite limited local recurrences, we demonstrate that even large and multifocal PICs may lack identifiable genomic alterations and are associated with benign outcomes.

Intra-Operative Diagnosis of Benign Multicystic Peritoneal Mesothelioma: A Case Report of Rare Entity and Lessons Learned

Benign multicystic peritoneal mesothelioma (BMPM), also known as multicystic peritoneal mesothelioma (MCPM), is a rare cystic neoplasm arising from the mesothelium lining of the abdominal and pelvic peritoneum. This entity has been disproportionately described in women of reproductive age. Both the etiology and pathogenesis of the condition are not well understood. Preoperative diagnosis is challenging as differentials are varied and include endometriosis, lymphangioma, pseudomyxoma peritonei, cystic adenomatoid tumor, and malignant peritoneal mesothelioma. Management options include cytoreductive surgery (CRS) with or without heated intraperitoneal chemotherapy (HIPEC). In this case report, we highlight the complexity of preoperative diagnosis, presentation, workup, treatment, and management of BMPM. We report the case of a female patient presenting with abdominal pain and imagining consistent with cystic intra-abdominal lesions. After an inconclusive percutaneous biopsy and a multi-disciplinary tumor board discussion, the patient was offered CRS with HIPEC. Intra-operative frozen section indicated benign epithelial lined cysts. CRS and HIPEC were performed. After a second opinion, the lesions were confirmed by pathology and immunohistochemistry to be BMPM. In this report, we discuss the gold standard of care for patients with BMPM to improve the disease control rate. This pathway is proposed in our study, and, thus, we conclude that BMPM should be considered in the differential diagnosis of patients presenting with symptomatic multiple intraperitoneal cystic lesions.

Primary splenic multicystic peritoneal mesothelioma in a young healthy male

Multicystic peritoneal mesothelioma (BMPM) is a rare, usually benign tumor that arises from peritoneal mesothelial cells that most commonly occurs in women of reproductive age. Pathogenesis of these tumors is thought to come from chronic inflammation from prior surgery, endometriosis, trauma, or recurrent peritonitis. Here we report a case of primary splenic BMPM in a 20-year-old male with no past medical or surgical history and without any typical risk factors for this condition. He underwent an open splenectomy without complication. Pathology revealed an 18 × 4 × 11 cm3 spleen with a cyst occupying 75% of the splenic surface. Sections revealed a multilocular cyst with trabeculated walls and immunohistochemical staining positive for cytokeratin (AE1/AE3) consistent with BMPM. One year post operatively he remains asymptomatic; however, his interval computed tomography (CT) scan revealed several sub centimeter nodules that either represents small splenules or neoplastic implants. These will be followed with close interval imaging.

Extrapelvic Endometriosis Mimicking Peritoneal Surface Malignancy: Case Report and a Review of Literature

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

Rare Variants of Malignant Peritoneal Mesothelioma: a Literature Review

Primary peritoneal mesothelioma (PM) is a rare and aggressive malignancy that arises from the peritoneum and classified into diffuse malignant peritoneum mesothelioma (DMPM) and borderline variants, viz. multicystic peritoneal mesothelioma (MCPM) and well-differentiated papillary peritoneal mesothelioma (WDPPM). The borderline variants are rarer than conventional DMPM, are less aggressive form accounting for 3-5% of all cases of peritoneal mesothelioma. In this narrative review article, we have discussed the pathogenesis, clinical presentation, natural history, and management of these rarer variants of PM, viz. MCPM and WDPPM. Histologically, MCPM typically consists of small cysts composed of mesothelial epithelium with benign bland cuboidal cells with clear fluids; cells lack cellular atypia and have increased number of mitoses. WDPPM has specific papillary component with myxoid plump cores and single layer of bland mesothelial cells. Both the variants commonly present as incidental finding or symptoms of chronic abdominal pain, chronic pelvic inflammatory disease, pelvic mass, and infertility. In the absence of treatment, these diseases are slow growing with major concerns being that both the variants have malignant transformation capabilities and a high rate of recurrence. In the light of current evidences, it is recommended that MCPM and WDPPM patients should be offered a complete cytoreductive surgery and hyperthermic intraperitoneal chemotherapy consisting of cisplatin and doxorubicin. Collaborative multi-institutional studies are needed to generate more data and formulate robust guidelines.

Communicating imaging findings in peritoneal mesothelioma: the impact of 'PAUSE' on surgical decision-making

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

Multicystic peritoneal mesothelioma treated with cytoreductive surgery followed or not by hyperthermic intraperitoneal chemotherapy: results from a large multicentric cohort

BACKGROUND

Multicystic peritoneal mesothelioma (MCPM) is a rare, slowly growing, condition prone to recur after surgery. The role of hyperthermic intraperitoneal chemotherapy (HIPEC) added to complete cytoreductive surgery (CRS) remains controversial and difficult to assess. As patients are mostly reproductive age women, surgical approach, and fertility considerations are important aspects of the management. This observational retrospective review aimed to accurate treatment strategy reflections.

METHODS

The RENAPE database (French expert centers network) was analyzed over a 1999-2019 period. MCPM patients treated with CRS were included. A special focus on HIPEC, mini-invasive approach, and fertility considerations was performed.

RESULTS

Overall 60 patients (50 women) were included with a median PCI of 10 (4-14) allowing 97% of complete surgery, followed by HIPEC in 82% of patients. A quarter of patients had a laparoscopic approach. Twelve patients (20%) recurred with a 3-year recurrence free survival of 84.2% (95% confidence interval 74.7-95.0). The hazard of recurrence was numerically reduced among patients receiving HIPEC, however, not statistically significant (hazard ratio 0.41, 0.12-1.42, p = 0.200). A severe post-operative adverse event occurred in 22% of patients with five patients submitted to a subsequent reoperation. Among four patients with a childbearing desire, three were successful (two had a laparoscopic-CRS-HIPEC and one a conventional CRS without HIPEC).

CONCLUSION

MCPM patients treatment should aim at a complete CRS. The intraoperative treatment options as laparoscopic approach, fertility function sparing and HIPEC should be discussed in expert centers to propose the most appropriate strategy.

New insights in the pathology of peritoneal surface malignancy

Pathology is central to the management of peritoneal surface malignancy. This article highlights some recent advances that have had an impact on patient management or could do so in the near future. Malignant peritoneal mesothelioma, particularly the epithelioid subtype, is amenable to radical therapy in selected cases, and factors such as ki67 proliferation index, expression of BAP1 and mutation in CDKN2A show promise as prognostic indicators. Our understanding of multicystic mesothelioma has improved in recent years; it is a true neoplasm for which surgery may be indicated. Serous carcinomas involving the peritoneum are now known to originate from tubal epithelium. They are of two distinct types, high grade and low grade, which are now recognized as different neoplasms with distinctive features, oncogenesis and behavior. Pseudomyxoma peritonei (PMP) is an unusual condition that usually arises from an appendiceal mucinous neoplasm. Recent consensus in the classification and nomenclature of these lesions is discussed, including the distinction between low grade and high grade appendiceal mucinous neoplasms (HAMN), and the diagnostic criteria for appendiceal adenocarcinoma. PMP is divided into four prognostic groups: acellular mucin, low grade mucinous carcinoma peritonei, high grade mucinous carcinoma peritonei, and high grade mucinous carcinoma peritonei with signet ring cells. The pseudomyxoma microbiome is a promising area for clinical intervention but has been the subject of little research activity. Goblet cell adenocarcinoma (previously known as 'goblet cell carcinoid') is a distinctive type of appendiceal adenocarcinoma. Its behavior correlates with histologic features, but no general consensus for classification has been reached.

Multicystic peritoneal mesothelioma treated with complete cytoreductive surgery, peritonectomy and hyperthermic intra-peritoneal chemotherapy-A case report

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Multicystic Peritoneal mesothelioma is a distinct type of peritoneal mesothelioma with borderline malignant potential and tendency to recur after tumor debulking.

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Morphologically MCPM has grapelike cysts filled with clear fluid and microscopically it has cystic spaces lined by cuboidal epithelium.

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There are areas of increased proliferative activity in the background of benign cyst representing potential for aggressiveness.

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Peritoneal free floating cysts can be formed from disintegration of main mass and deposit in other areas to form metastatic deposits.

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Comprehensive treatment – Complete cytoreduction, involved peritonectomy and HIPEC is required for treatment of macroscopic tumor and microscopic residue.

Background

Multicystic Peritoneal mesothelioma is a rare and distinct variety of peritoneal mesothelioma with borderline malignant potential. Conventional Tumor bulking has been associated with recurrence of 45–50 %. Hence a comprehensive treatment with Complete cytoreductive surgery with involved field peritonectomy (CRS) and Hyperthermic Intra-peritoneal chemotherapy (HIPEC) is being increasingly adopted for MCPM.

Case presentation

A 47 year old lady evaluated for peri-menopausal disturbance was diagnosed to have a multicystic lesion in the pelvis. With a preoperative suspicion of diagnosis of pseudomyxoma peritonei, CRS with HIPEC was planned. On exploration a diffuse multicystic mass was found in omentum and pouch of douglas with typical morphological features of MCPM. Complete cytoreduction was achieved with anterolateral and sub-diaphragmatic peritonectomy, omentectomy and panhystrectomy. HIPEC was performed with cisplatin 50 mg/m² for 40 min. Pathological examination revealed MCPM of omentum and uterine surface with focal clusters of mesothelial proliferation. However there was low proliferative activity 1–2 %.

Discussion

MCPM presents with wide spread peritoneal spread but with relative sparing of visceral invasion. Literature review suggests the disease spread is similar to PMP and treatment with CCRS and HIPEC has yielded long term survivals in MCPM.

Conclusions

This patient with voluminous disease burden in abdomen required surgical management and HIPEC for her condition. Whether CCRS alone without HIPEC can be an alternative for limited disease will be interesting research for future clinical reports.

Multicystic and diffuse malignant peritoneal mesothelioma in children

BACKGROUND

Malignant and multicystic peritoneal mesotheliomas are extremely rare tumors in children, developing from mesothelial cells. No specific guidelines are available at this age.

METHODS

We performed a retrospective analysis of all identified children (< 18-year-old) treated in France from 1987 to 2017 for a diffuse malignant peritoneal mesothelioma (DMPM) or a multicystic peritoneal mesothelioma (MCPM).

RESULTS

Fourteen patients (5 males and nine females), aged 2.2 to 17.5 years, were included. The most frequent presenting symptoms were abdominal pain, ascitis, and alteration in the general condition. Eight patients had epithelioid mesothelioma, three had biphasic mesothelioma, and three had MCPM. Eight patients with DMPM diagnosis received cytoreductive surgery (CRS) with hyperthermic intraperitoneal chemotherapy (HIPEC). Among them, six patients had neoadjuvant systemic chemotherapy, one patient, post-operative chemotherapy, and one patient CRS and HIPEC only. Three patients received only systemic chemotherapy. All patients with MCPM had only surgery. After a median follow-up of seven years (2-15), six patients (6/11; one death) with DMPM and two patients (two/three) with MCPM had a local and distant recurrences.

CONCLUSION

Peritoneal mesothelioma in children is a rare condition with difficult diagnosis and high risk of recurrence. Worldwide interdisciplinary collaboration and networking are mandatory to help diagnosis and provide harmonious treatment guidelines.

Multicystic peritoneal mesothelioma: a systematic review of the literature

Multicystic peritoneal mesothelioma (MCPM) is a particularly rare and benign neoplasm that arises from the peritoneum in reproductive aged females. Its etiopathogenesis is still unclear. The current prevailing theory supports the idea that the tumor is the result of an excessive inflammatory process. Because of a lack of clinical and imaging presentation, the diagnosis is intricate, and heavily relies on case reports and short studies. A histological analysis with immunohistochemistry is required for a definitive diagnosis. To date, there is no standard treatment recommended for MCPM. However, some studies suggest proceeding with a cytoreductive surgery and a hyperthermic intraperitoneal chemotherapy combining CISPLATIN and DOXORUBICIN, due to a high incidence of recurrence rate after medical treatment or surgery alone and potential malignant transformation.

Analysis of Bacterial and Fungal Infections after Cytoreduction Surgery and Hyperthermic Intraperitoneal Chemotherapy: An Observational Single-Centre Study

Introduction

While hyperthermic intraperitoneal chemotherapy (HIPEC) after cytoreduction surgery (CRS) has been shown to improve patient survival and disease-free progression in peritoneal carcinoma (PC) patients, the procedure relates to a high postoperative infection rate. Herein, we report the bacterial and fungal infections after CRS and HIPEC from a single institution in Saudi Arabia.

Patients and Methods

A prospective observational study was conducted on 38 patients with PC selected for CRS/HIPEC procedure between 2012 and 2015 in our centre.

Results

Postoperative bacterial and fungal infection within 100 days was 42.2%, bacterial infection was reported always, and fungal infection was reported in 5 (13.2%) cases. Infections from the surgical site were considered the most common infection site. Multidrug-resistant extended-spectrum beta-lactamase (ESBL) Escherichia coli was the most frequent isolate, followed by multidrug-resistant Acinetobacter baumannii and Pseudomonas aeruginosa. Lower preoperative albumin and a prolonged preoperative activated partial thromboplastin time (APTT) are associated with postoperative infections, while a prolonged preoperative hospital stay (hazard ratio (HR) = 1.064; confidence interval (CI) = 1.002–1.112; P=0.042) and more intraoperative blood loss (>10%) (HR = 3.919; 95% CI = 1.024–14.995; P=0.046) were independent risk factors for postoperative infections. Three cases died during the follow-up period; all were due to infection.

Discussion

The infection rate in our centre compared to previous studies of comparable patients was matching. Effective management of postoperative infections should be considered, and identified risk factors in this study can help to focus on effective prevention and treatment strategies.

Benign Multicystic Peritoneal Mesothelioma (BMPM) as a rare cause of abdominal pain in a young male: case report and review of the literature

Benign Multicystic Peritoneal Mesothelioma (BMPM) is a rare benign cystic neoplasm that arise from the peritoneum, typically found in young females (83%), with a high incidence of local recurrence after resection (almost 50% of cases). Fewer than 200 cases have been reported worldwide in 2017. Due to its rarity and the lack of a classical clinical presentation, the diagnosis pre-operatively is challenging; moreover a great part of the literature is composed of case reports and small group studies. Nowadays, guidelines are still not available, and treatment is en bloc resection of the lesion. Some authors suggest the use of Hyperthermic Intraperitoneal Chemotherapy (HIPEC) associated with the surgical approach, even if comparative data on recurrence and complications are lacking. We report a case of BMPM diagnosed in a 40-year-old male who underwent an exploratory laparoscopy and complete excision of the neoformation. Pathology confirmed the presence of a BMPM.

Benign Multicystic Peritoneal Mesothelioma in a Male Patient with Previous Wilms' Tumor: A Case Report and Review of the Literature

Benign multicystic peritoneal mesothelioma (BMPM) is a rare condition, more common in females of reproductive age, which arises from the peritoneal mesothelium. A 33-year-old male presented to our unit with abdominal pain and constipation. His past medical history included a previous unilateral nephrectomy for Wilms' tumor and the previous incidental finding of some intra-abdominal cystic formations at the level of the mesentery. After performing a CT scan, an exploratory laparotomy was done and a voluminous cystic mesenteric mass, composed of 3 confluent formations, was observed. Some other similar but significantly smaller lesions were found. An en bloc resection of the mesenteric mass together with the corresponding intestinal loops, an appendicectomy, and some peritoneal biopsies were performed. The postoperative period was complicated by a peritonitis due to dehiscence of the intestinal anastomosis, which required another operation, and a delayed return of normal bowel function, which was resolved through prokinetic therapy. Through histological examination, a BMPM was diagnosed. At 8 months of follow-up, the patient is free of symptoms. BMPM exact etiopathogenesis still remains uncertain. Given his high recurrence rate, a long-term follow-up is recommended.

Malignant Peritoneal Mesothelioma: National Practice Patterns, Outcomes, and Predictors of Survival

PURPOSE

This study of a large, contemporary national database evaluated management patterns, outcomes, and prognostic factors of malignant peritoneal mesothelioma (MPM) in the USA.

METHODS

The National Cancer Data Base was queried for newly diagnosed nonmetastatic MPM. Patients were divided into five cohorts: observation, chemotherapy alone, cytoreductive surgery (CRS) alone, CRS/chemo [referring to any non-hyperthermic intraperitoneal chemotherapy (HIPEC) chemotherapy], and CRS/HIPEC. Statistics included multivariable logistic regression, Kaplan-Meier analysis, and Cox proportional hazards modeling.

RESULTS

Of 1514 patients, 379 (25%) underwent observation, 370 (24%) received chemotherapy only, 197 (13%) CRS alone, 352 (23%) CRS/chemo, and 216 (14%) CRS/HIPEC. No major temporal trends in management were noted. Factors predictive of CRS administration included younger age, female gender, insurance status, residence in educated areas, living farther from treating institutions, and treatment at academic centers (p < 0.05 for all). Compared with epithelioid histology, those with sarcomatoid and biphasic histology were less and more likely to undergo CRS, respectively (p < 0.05 for both). In all CRS patients, 30- and 90-day mortality rates were 0.8 and 1.2%, respectively. At median follow-up of 50 months, median OS in the respective groups was 6, 17, 21, 52, and 61 months (p < 0.001). Poor prognostic factors included advanced age, male gender, uninsured/Medicaid insurance, and sarcomatoid/biphasic histology (p < 0.05 for all).

CONCLUSIONS

In the USA, MPM is treated using a wide variety of strategies. Many factors impact the type of treatment delivered, including age, sociodemographics, geography, histology, and facility type. Although these data do not imply causation, combined-modality management seems associated with the longest OS.

Multicystic mesothelioma: Operative and long-term outcomes with cytoreductive surgery and hyperthermic intra peritoneal chemotherapy

BACKGROUND

Multicystic peritoneal mesothelioma (MCPM) is an extremely rare disease with 40-50% rate of recurrence after surgical debulking. Due to the recurrent nature of the disease, the option of cytoreductive surgery combined with hyperthermic intraperitoneal chemotherapy (HIPEC) was offered for this condition. In the present study we aimed to describe the outcomes of this strategy in a single center cohort.

METHODS

We retrospectively reviewed a prospectively collected database of all patients with MCPM that underwent the combined procedure in our center. Clinical presentation, operative procedures and outcomes were reviewed.

RESULTS

Between August 1997 and October 2017, 19 patients with MCPM underwent 20 cytoreduction and HIPEC procedures in our center. The majority of the patients were females (n = 17, 89%), and mean age was 42, as reported in other series. Disease extent, as measured by mean peritoneal carcinomatosis index (PCI) was 15.5 ± 9.9 and total number of procedures performed 6.7 ± 2.6. Major complications occurred in 3 (15%) patients, with no perioperative mortality. After a median of follow-up of 69 months (range 4-220) all patients were alive and 4 patients had recurrence (21%). Patients with high PCI (defined by median PCI) had shorter recurrence free survival (RFS) than patient with low PCI (mean RFS = 106.4 ± 6.6 for high PCI vs. 125.6 ± 34.1 for low PCI, p = 0.03).

CONCLUSION

Cytoreduction and HIPEC offer low recurrence rate and prolonged mean RFS for patients with MCPM. The combined procedure can be offered with acceptable morbidity in specialized centers.

Clinical presentation, diagnosis, classification and management of peritoneal mesothelioma: a review

Peritoneal mesothelioma (PM) is an uncommon but a serious, and often, fatal primary peritoneal tumour, with increasing incidence worldwide. Conventional systemic chemotherapy, generally based on experience with pleural mesothelioma, usually has disappointing results considering PM as a terminal condition. Patients usually present with non-specific symptoms of abdominal distension and pain making the diagnosis challenging. As PM is confined to the abdomen for all, or much, of its clinical course, a multimodality treatment combining cytoreductive surgery (CRS) with hyperthermic intraperitoneal chemotherapy (HIPEC) has emerged as a new standard of care, and has been reported to achieve promising survival outcomes and local disease control in selected patients with PM. This review updates the presentation, diagnosis, classification and treatment strategies for PM.

Benign Multicystic Peritoneal Mesothelioma: A Rare Condition in an Uncommon Gender

Benign Multicystic Peritoneal Mesothelioma (BMPM) is a rare condition that arises from the abdominal peritoneum. Fewer than 200 cases have been reported worldwide. BMPM usually affects premenopausal women and is extremely rare in men. Many factors are suspected to contribute to its development, such as previous surgery, endometriosis, and familial Mediterranean fever. The main management is surgical resection; however, it is estimated that the recurrence rate is up to 50%. Malignant transformation is rare. We report a case series of three male patients who were diagnosed with BMPM and were treated with cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (HIPEC).

The RENAPE observational registry: rationale and framework of the rare peritoneal tumors French patient registry

Background

Rare peritoneal cancers represent complex clinical situations requiring a specific and multidisciplinary management. Because of their rarity, lack of awareness and knowledge often leads to diagnostic delays and misdiagnosis. And patients are not systematically referred to expert centers as they should be. Clinicians and researchers also face unique challenges with these rare cancers, because it is hard to conduct adequately powered, controlled trials in such small patient population. This is how an observational patient registry constitutes a key instrument for the development of epidemiological and clinical research in the field of these rare cancers. It is the appropriate tool to pool scarce data for epidemiological research and to assess the impact of diagnostic and therapeutic strategies. We aimed to provide the outlines and the framework of the RENAPE observational registry and share our experience in the establishment of a national patient registry.

Results

The RENAPE observational registry has been launched in 2010 thanks to institutional supports. It concerns only patients with a histological diagnosis confirming a peritoneal surface malignancy. A web secured clinical database has been implemented based on data management procedures according to the principles of international recommendations and regulatory statements. A virtual tumor bank is linked in order to the conduct translational studies. Specialized working groups have been established to continuously upgrade and evolve the common clinical and histological data elements following the last classifications and clinical practices. They contribute also to standardize clinical assessment and homogenize practices.

Conclusions

The RENAPE Registry may improve awareness and understanding of the rare peritoneal tumors into the incidence, prevalence, recurrence, survival and mortality rates, as well as treatment practices thereby enabling therapeutic intervention to be evaluated and ultimately optimized.

Trial registration

ClinicalTrials.gov Identifier: NCT02834169

Peritoneal mesothelioma: the site of origin matters

The etiology, gender distribution, pathology, natural history, and treatment options for mesothelioma (MM) differ substantially depending on the site of origin. Peritoneal mesothelioma (MPeM) is a rare disease, comprising only approximately 10% to 15% of the 2,500 cases of MM diagnosed in the United States each year. Patients with MPeM are younger than patients with pleural MM, and a higher proportion, mostly women, are long-term survivors. Most MPeM is caused by asbestos exposure. Germ-line mutations of BAP1 (BRCA associated protein 1) can predispose to MM, uveal melanoma, and potentially other cancers. MPeM can be challenging to diagnose, and cytology is rarely helpful. Review by an experienced pathologist using a panel of at least two positive and two negative immunohistochemical stains is essential. The three major pathologic subtypes are epithelial, sarcomatoid, and biphasic. Most cases are epithelial; the others have a dismal prognosis. Two indolent subtypes of borderline malignant potential-well-differentiated papillary mesothelioma and benign multicystic mesothelioma-are more common in the peritoneum and are treated surgically. In highly selected patients receiving treatment at experienced referral centers, an aggressive locoregional strategy that combines cytoreductive surgery to remove all gross disease and hyperthermic intraperitoneal chemotherapy to treat residual microscopic tumors yields a 3-year survival of 60% and a median survival approaching 5 years, far better than expected from historic controls. This approach also provides durable palliation of malignant ascites in nearly all patients. Pemetrexed is the only U.S. Food and Drug Administration (FDA)-approved systemic chemotherapy for pleural MM. Largely on the basis of data from pharmaceutical registry studies, the activity of pemetrexed-based chemotherapy appears to be similar in pleural MM and MPeM.

Cytoreductive surgery and intraperitoneal chemotherapy: an evidence-based review-past, present and future

Peritoneal carcinomatosis (PC) has historically been considered a terminal condition with merely palliative treatment achieving a survival rate measured in months. Cytoreductive surgery (CyRS) and intraperitoneal chemotherapy (IPC) have emerged as potentially effective regional treatments with the potential for long-term survival in well-selected patients. The fundamentals of CyRS and IPC are patient selection and complete cytoreduction. Since there is now sufficient evidence for the superiority of CyRS and IPC to systemic chemotherapy alone in a highly select group of patients, surgeons and oncologists should be aware of this modality as a potential benefit for patients with PC. The aim of this report is to highlight cancer-specific evidence in the context of ongoing studies regarding the outcome of this treatment.

Benign multicystic mesothelioma of peritoneum complicating acute appendicitis in a man: a case report

BACKGROUND

Benign multicystic mesothelioma is a rare pathology. Few cases are reported in the medical literature and acute presentation is extremely uncommon.

CASE PRESENTATION

We describe an acute clinical presentation of the neoplasm that revealed itself with signs and symptoms attributable to acute appendicitis in a 41-year-old white man. Abdominal echography and computed tomography scans demonstrated the presence of a mass in direct contiguity with cecal fundus, but diagnosis remained unclear. Our patient underwent surgery and complete removal of the neoplasm. Only a definitive histological examination defined the nature of the lesion. No signs of relapse were demonstrated 1 year after the operation.

CONCLUSIONS

We showed that an acute presentation of a benign neoplasm represents a diagnostic and therapeutic challenge for the surgeon, because of the difficult differential diagnosis that acute presentation can sometimes pose and the trouble that an emergence treatment can imply.

Diffuse mesothelioma of the peritoneum: correlation between histological and clinical parameters and survival in 73 patients

There are few studies addressing survival of diffuse peritoneal mesotheliomas (DPM).In this study, survival data were obtained retrospectively from 73 patients treated with intended cytoreductive surgery for DPM, with a mean follow-up of 42 months. Mesotheliomas were classified as well differentiated papillary (WDPM, n = 2), multicystic (MCM, n = 4), and epithelioid mesotheliomas were subclassified as tubulopapillary (TPM, n = 27), solid/deciduoid (S/DM, n = 34), and or biphasic mesothelioma (BPM, n = 6). Invasion was characterised as absent (grade 0), into stroma (grade 1), into fat (grade 2), and into adjacent structures (grade 3). Peritoneal cancer index (PCI) and completeness of cytoreduction (CCR) were assessed surgically.There were no deaths in the WDPM, MCM, and epithelioid DPM with ≤ grade 1 invasion. There was a stepwise decrease in overall survival from invasive TPM, S/DM, and BPM (p < 0.0001). By univariate analysis, advanced age (p = 0.01), incomplete CCR (p < 0.001), PCI (p = 0.004), mitotic count (p < 0.001), nuclear grade (p < 0.0001), stromal inflammation (p = 0.013), depth of invasion (p < 0.0001), necrosis (p = 0.002), and sarcomatoid growth (p < 0.0001) were associated with decreased overall survival. By multivariate analysis, only sarcomatoid growth (p = 0.0006), depth of invasion (p = 0.02), elevated CCR (CCR 2-3) (p = 0.02), and presence of inflammatory stroma (p = 0.04) were significant variables associated with decreased overall survival.DPM form a spectrum of indolent to highly aggressive tumours. Solid epithelioid/deciduoid tumours have a prognosis intermediate between biphasic mesotheliomas and invasive TPM. The presence and degree of invasion, sarcomatoid features, and inflammatory stroma are poor prognostic indicators.

Novel TNS3-MAP3K3 and ZFPM2-ELF5 fusion genes identified by RNA sequencing in multicystic mesothelioma with t(7;17)(p12;q23) and t(8;11)(q23;p13)

Multicystic mesothelioma is a rare disease of unknown etiology and pathogenesis. Nothing has been known about the cytogenetic and molecular genetic features of these tumors. Here we present the first cytogenetically analyzed multicystic mesothelioma with the karyotype 46,XX,t(7;17)(p13;q23),t(8;11)(q23;p13). RNA-sequencing showed that the t(7;17)(p13;q23) generated a chimeric TNS3-MAP3K3 gene, which codes for a chimeric protein kinase, as well as the reciprocal MAP3K3-TNS3 in which the region of TNS3 coding for the SH2_Tensin_like region and the tensin phosphotyrosine-binding domain is under the control of the MAP3K3 promoter. The other translocation, t(8;11)(q23;p13), generated a chimeric ZFPM2-ELF5 gene which codes for a chimeric transcription factor in which the first 40 amino acids of ELF5 are replaced by the first 100 amino acids of ZFPM2. RT-PCR together with Sanger sequencing verified the presence of the above-mentioned fusion transcripts. The finding of acquired clonal chromosome abnormalities in cells cultured from the lesion and the presence of the TNS3-MAP3K3 chimeric protein kinase and the ZFPM2-ELF5 chimeric transcription factor confirm the neoplastic nature of multicystic mesothelioma.

Advances in the management of peritoneal mesothelioma

Malignant peritoneal mesothelioma (PM) is an infrequent disease which has historically been associated with a poor prognosis. Given its long latency period and non-specific symptomatology, a diagnosis of PM can be suggested by occupational exposure history, but ultimately relies heavily on imaging and diagnostic biopsy. Early treatment options including palliative operative debulking, intraperitoneal chemotherapy, and systemic chemotherapy have marginally improved the natural course of the disease with median survival being approximately one year. The advent of cytoreduction (CRS) with hyperthermic intraperitoneal chemotherapy (HIPEC) has dramatically improved survival outcomes with wide median survival estimates between 2.5 to 9 years; these studies however remain largely heterogeneous, with differing study populations, tumor biology, and specific treatment regimens. More recent investigations have explored extent of cytoreduction, repeated operative intervention, and choice of chemotherapy but have been unable to offer definitive conclusions. CRS and HIPEC remain morbid procedures with complication rates ranging between 30% to 46% in larger series. Accordingly, an increasing interest in identifying molecular targets and developing targeted therapies is emerging. Among such novel targets is sphingosine kinase 1 (SphK1) which regulates the production of sphingosine-1-phosphate, a biologically active lipid implicated in various cancers including malignant mesothelioma. The known action of specific SphK inhibitors may warrant further exploration in peritoneal disease.

Cytoreductive surgery and hyperthermic intraperitoneal chemotherapy for malignant peritoneal mesothelioma: a systematic review and meta-analysis

BACKGROUND

Due to the increased adoption of cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC), patients with malignant peritoneal mesothelioma (MPM) have seen improved outcomes. We aimed to evaluate and synthesize the recent published literature.

METHODS

The review was conducted according to the recommendation of the Meta-Analysis of Observational Studies in Epidemiology group with prespecified inclusion and exclusion criteria. The DEALE method was used to combine mortality rates, and imputation techniques were used to calculate standard errors. Meta-regression techniques were used to synthesize data. Publication bias was assessed using funnel plots.

RESULTS

Of 6,528 citations collected, 20 articles reporting on 1,047 patients were included in the analysis. The median age was 51 years (interquartile range 49-55), with 59 % (54-67) female. The median peritoneal carcinomatosis index score was 19 (16-23). Complete cytoreduction (CC0, 1) was performed in 67 % (46-93 %) of patients. Pooled estimates of survival yielded a 1-, 3- and 5-year survival of 84, 59, and 42 %, respectively. Patients receiving early postoperative intraperitoneal chemotherapy [EPIC] (44 %) and those receiving cisplatin intraperitoneal chemotherapy alone (48 %) or in combination (44 %) had an improved 5-year survival.

CONCLUSIONS

While CRS + HIPEC has led to an improved survival for patients with MPM compared to historic data, heterogeneity of studies precludes generalizable inferences. EPIC chemotherapy and cisplatin chemoperfusion may infer survival benefit.

Diffuse mesothelioma of the peritoneum: a pathological study of 64 tumours treated with cytoreductive therapy

BACKGROUND

Diffuse peritoneal mesothelioma (DPM) forms a spectrum of indolent surface tumours to malignant invasive cancers. There are few pathological series that span well and poorly differentiated lesions that show diffuse peritoneal spread.

METHODS

Sixty-four DPM treated by initial cytoreductive therapy were retrospectively reviewed. Tumours were classified by surface and invasive growth pattern and correlated with risk factors, peritoneal cancer index (PCI) and completeness of cytoreduction (CCR). Degree of invasion was quantitated as absent (0), into stroma (I), into fat (II), and into adjacent structures (III) and was correlated with cytological features. Selected immunohistochemical stains were performed.

RESULTS

There were three well differentiated papillary mesotheliomas (WDPM; type A), four multicystic mesothelioma (type B), 22 tubulopapillary epithelioid mesotheliomas (type C), and 35 poorly differentiated epithelioid mesotheliomas with solid or sarcomatoid growth (Type D). Seven type D tumours had prominent sarcomatoid areas, 12 deciduoid areas, and four lymphohistiocytoid features. Risk factors were present in all groups except type A, and included prior abdominal surgery (n=24), asbestos exposure (n=5) and radiation (n=2). Extra-pleural mesothelioma was present in all groups except type B (total n=7, 11%). Two type A and eight type C tumours lacked invasion; only type D showed level III invasion. The invasive portion of one type A tumour and two type B tumours showed adenomatoid features. PCI and CCR were greater in type D compared to the other groups (p=0.02), as well as mitotic rate, degree of necrosis, and nuclear pleomorphism (p<0.001). Degree of invasion was strongly correlated with CCR (p=0.007), necrosis (p<0.0001), nuclear grade (p<0.0001), and mitotic rate (p=0.001), but not PCI (p=0.1). Immunohistochemical results were similar across groups, with frequent positivity for CA125 (94%), EGFR (94%) and calretinin (93%), followed by p16 (85%), cytokeratin 5,6 (76%), D2-40 (71%) and WT-1 (47%). PAX-8 was negative in all tumours, except one type A tumour that showed diffuse nuclear positivity.

CONCLUSIONS

Diffuse peritoneal mesotheliomas can be classified into four groups that reflect invasive potential, degree of adverse histological features, and amenability for CCR. Non-invasive tumours include both type A and type C tumours.

Peritoneal debulking/intraperitoneal chemotherapy-non-sarcoma

The combination of cytoreductive surgery (CRS) and intraperitoneal chemotherapy (IPC) is widely practiced for appendiceal, colorectal, gastric, and ovarian cancers with isolated peritoneal metastasis as well as for primary peritoneal cancer. The aim of this report is to explain the rationale and available techniques for CRS and IPC, and to highlight disease-specific considerations that should be taken into account when evaluating potential candidates for CRS and IPC.

Development of regional chemotherapies: feasibility, safety and efficacy in clinical use and preclinical studies

Conventional oral and intravenous chemotherapies permeate throughout the body, exposing healthy tissues to similar cytotoxic drug levels as tumors. This leads to significant dose-limiting toxicities that may prevent patients from receiving sufficient treatment to overcome cancers. Therefore, a number of locoregional drug-delivery strategies have been evaluated and implemented in preclinical studies, clinical trials and in practice, in the past decades to minimize systemic toxicities from chemotherapeutic agents and to improve treatment outcomes. Localized treatment is beneficial because many cancers, such as melanoma, peritoneal cancer and breast cancer, advance locally adjacent to the site of the primary tumors prior to their circulatory invasion. In this article, we will review the feasibility, safety and efficacy of multiple localized chemotherapies in clinical use and preclinical development.