Well-Differentiated Papillary Mesothelioma of the Peritoneum: A Retrospective Study from the RENAPE Observational Registry

BackgroundWell-differentiated papillary mesothelioma of the peritoneum (WDPMP) is a rare entity. Questions regarding management are still being debated as no more than 50 cases have been reported in the literature.ObjectiveWe aimed to analyze the clinical, therapeutic, and prognostic data of patients with WDPMP from the RENAPE observational registry.Patients and MethodsAll patients diagnosed with WDPMP and prospectively included in the RENAPE national registry between 2010 and 2018 were also included in our study. Expert pathologists from the RENA-PATH group confirmed all cases. All clinical, therapeutic, postoperative, and prognostic data were extracted and analyzed.ResultsWe report on 56 patients with a mean age of 52years (range 21-74). WDPMP was incidentally diagnosed during imaging or surgery in 16% and 36% of patients, respectively, and an association with synchronous malignancy was found in 18% of patients. Nine lesions showed discrete signs of fatty invasion. The median Peritoneal Cancer Index was 11 (range 0-33). Eleven patients were treated with definitive excision, 4 were treated with cytoreductive surgery (CRS) only, 37 were treated with CRS and hyperthermic intraperitoneal chemotherapy (HIPEC), and 2 were treated with CRS plus HIPEC plus early postoperative intraperitoneal chemotherapy. CRS was considered to be complete in 90% of cases. One patient died postoperatively and 16 patients (31%) faced postoperative complications. The median disease-free survival was 144months; Four patients relapsed, with a median period of 27months. No prognostic factors could be identified.ConclusionsOur analysis confirms the favorable prognosis of WDPMP. CRS and HIPEC could be a therapeutic option for diffuse, symptomatic, and/or recurrent disease.