Correlation between peritoneal mesothelial cell cytology and peritoneal histopathology with respect to prognosis in patients on continuous ambulatoryperitoneal dialysis

Background: Sclerosing encapsulating peritonitis (SEP) is a serious complic ation seen in patients on long-term continuous ambulatory peritoneal dialys is (CAPD). We have previously reported that mesothelial cells in effluent d ialysate significantly increased in size as the duration of CAPD progressed . In this study, we investigated the relationship between mesothelial cytol ogy, histopathology of the peritoneum, and clinical outcomes of 34 CAPD pat ients. Methods. When peritoneal dialysis catheters were inserted (n = 7) or removed (n = 27), a peritoneal biopsy was performed and results compared w ith mesothelial cytology in effluent dialysate. Results: A significant posi tive correlation was noted between the duration of CAPD and the surface are a of peritoneal mesothelial cells (r = 0.721, p < 0.0001). The surface area of mesothelial cells in peritoneal sclerosis (n = 9; 584 +/- 97 <mu>m(2)) was significantly greater than in peritoneal fibrosis (n = 14; 389 +/- 26 m um(2), p < 0.05), pathologic acute peritonitis (n = 3; 223 +/- 10 <mu>m(2), p < 0.005), and normal peritoneum (n = 7; 247 +/- 12 <mu>m(2), p < 0.001). The surface area in sclerosing peritonitis (n = 1; 1,200 <mu>m(2)) was gre ater than that of all the others. Giant cells were found in the 1 case with sclerosing peritonitis and in 3 of 9 cases with peritoneal sclerosis, alth ough they were found in only 1 of 14 patients with peritoneal fibrosis and in none of those with pathologic acute peritonitis or normal peritoneum. As the surface area of mesothelial cells increased to more than 400 mum(2) an d giant cells appeared in the effluent, the frequency of peritoneal scleros is and/or clinical SEP increased. Conclusion: An increase in the mesothelia l cell surface area and the emergence of giant cells in the effluent indica te advanced peritoneal histopathology, and may be useful indicators to dete rmine appropriate timing of discontinuation of CAPD to prevent the developm ent of SEP. Copyright (C) 2001 S. Karger AG, Basel.