[Peritoneal pseudomyxoma: an overview emphasizing pathological assessment and therapeutic strategies]

[RENAPE network: Towards more equitable access to care and expertise for patients with rare peritoneal cancers]

Since its creation in 2010, the progressive structuration of the RENAPE network (Réseau national de prise en charge des tumeurs rares du péritoine) supported by the "Institut national du cancer" and the "Direction générale de l'offre de soins", allowed the optimization of the healthcare system involved in the management of the rare cancers of the peritoneum. In this setting, the RENA-PATH group has also been reinforced, notably by its recognized diagnostic expertise in pathology and its interface with the MESOPATH group. Moreover RENAPE and RENA-PATH led to guidelines diffusion through the integration, in 2019, to the ``Thesaurus National de Cancérologie Digestive'' (TNCD) and to post-university medical education programs. The aim of this article is to highlight the missions of the RENAPE and RENA-PATH, notably the equity in terms of expertise, access to the networks and their improvement in the management of peritoneal diseases.

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.

Liver scalloping: Pseudomyxoma peritonei liver compression

Pseudomyxoma peritonei is a rare tumor characterized by the presence of mucous disseminated throughout the peritoneal cavity generally arising from the rupture of an appendicular mucocele. Liver scalloping is a highly suggestive image of pseudomyxoma and corresponds to the indentation of the liver compressed by the gelatinous mucin.

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

Pseudomyxoma peritonei diagnosed 19 years after appendicectomy

Pseudomyxoma peritonei (PMP) is an uncommon clinical finding describing the intraperitoneal accumulation of abundant mucinous, jelly-like material. This entity may represent a spectrum of diseases ranging from mucinous ascites, commonly associated with ruptured epithelial tumours of the appendix, to frank mucinous carcinomatosis. In cases of appendiceal origin, the patient may present with signs and symptoms of acute appendicitis, and thus careful diagnosis must be made in order to correctly and appropriately guide management. This may include a combination of surgical debulking with or without intraperitoneal or systemic chemotherapy. We present a 52-year-old woman with a 4-month history of abdominal pain and distension with a previous appendicectomy 19 years earlier. Radiological and pathological investigations diagnosed a probable PMP secondary to ruptured appendicitis many years ago. We describe her unique case, with emphasis on length of time to diagnosis and clinical management by surgical cytoreduction alone.