Sclerosing peritonitis: a nosological entity.

The peritoneal histology of 224 peritoneal dialysis (PD) patients without sclerosing peritonitis (SP) and of 39 PD patients with SP was evaluated. Of the 224 patients, 180 showed simple sclerosis (SS). In these subjects, slight thickness of sclerosis (10 - 70 microm), slight parvicellular infiltration (5/180), slight arterial thickening with no vessel occlusion (19/180), and slight tissue calcification (1/180) were observed. In the 39 patients with SP, striking histological changes versus SS were detected: thickness of sclerosis 250 - 4000 microm, p < 0.01; inflammation 39/39, p < 0.01 (parvicellular infiltration 36/39, p < 0.01; microabscesses 15/39, p < 0.05; giant cells 38/39, p < 0.01; granulation tissue 38/39, p < 0.01); arterial alterations 39/39, p < 0.01 (thickening 39/39, p < 0.01; occlusion 39/39, p < 0.01; calcification 26/39, p < 0.01; ossification 9/39, p < 0.01); tissue calcification 12/39, p < 0.01 (with ossification 4/39, with bone marrow 2/39). The thickness of sclerosis in SS was higher in parietal (30 - 70 microm) than in visceral peritoneum (10 - 40 microm, p < 0.05); in SP it was higher in visceral (600 - 4000 microm) than in parietal peritoneum (250 - 2000 microm, p < 0.05). These striking differences suggest consideration of SS and SP as two separate nosological entities. Differences in frequency, animal models, etiology, and clinical impact seem to confirm this hypothesis, showing that SP is not just the evolution of SS.