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

ABSTRACT

BACKGROUND: Well-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. OBJECTIVE: We aimed to analyze the clinical, therapeutic, and prognostic data of patients with WDPMP from the RENAPE observational registry. PATIENTS AND METHODS: All 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. RESULTS: We report on 56 patients with a mean age of 52 years (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 144 months; Four patients relapsed, with a median period of 27 months. No prognostic factors could be identified. CONCLUSIONS: Our analysis confirms the favorable prognosis of WDPMP. CRS and HIPEC could be a therapeutic option for diffuse, symptomatic, and/or recurrent disease.