Multicystic mesothelioma has malignant potential: its grounds and mechanisms of peritoneal metastasis

Abstract

From 2009 to 2016, 9 female patients with multicystic peritoneal mesothelioma (MCPM) underwent 11 cytoreductive surgeries (CRS). Mean age at diagnosis was 50.6 (range, 43-71). Mean peritoneal cancer index was 8.9 (range, 2~33).Most frequent peritoneal sector involved was pelvic peritoneum in 7 patients, and greater omentum was involved in 6 patients. Eight and 1 patients had complete CRS and incomplete CRS, respectively. Except 1 patient, 8 patients had multiple cysts on different peritoneal sectors, and diffuse involvement on peritoneal surface was found in 2 patients No patients had lymph node metastasis or extraperitoneal spread. However, 3 patients showed pushing invasion to small bowel mesentery, colon, umbilicus and stomach. Median-follow-up was 46 months (range 4-120). At the time of the present analysis, all patients were alive. One patient recurred in peritoneal cavity 47 month after complete cytoreduction.Peritoneal free-floating cysts (PFFC) were found in 8 of 9 (88.9%) patients. Sizes of PFFC ranged from 1 mm to 2 cm in diameter and the inner surfaces were covered with mesotheliallike cells. MIB-1 labeling rates of PFFC ranged from 0.1% to 2.0%. These results indicate that PFCC may attach on the orifice of subperitoneal lymphatic vessels, and may become metastatic.The present study strongly suggests that MCPM has a potentially malignant behavior. This category of disease is composed of 2 types: diffuse type and localized type with borderline malignant potential. PFFC have an important role in the formation of peritoneal metastasis.

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

“…Though MCPM is reported to be a benign etiology by some, several others have reported instances of malignant transformation and co-existent DMPM in these patients [ 4 , [12] , [13] , [14] ]. In general, MCPM pathologically has multicystic or unilocular cystic lesions lined by single layer of cuboidal or flat mesothelial cells with no atypia.…”

“…Another interesting pathological finding we observed was the presence of Peritoneal free floating cysts (PFFC) in the peritoneal cavity. Yonemura et al has reported these Peritoneal free floating cysts (PFFC) in 8/9 MCPM patients in their series [ 13 ]. Some of the cysts attached to the main mass through a thin stalk and can disintegrate easily ( Fig.…”