Comparison between the pathology of encapsulating sclerosis and simple sclerosis of the peritoneal membrane in chronic peritoneal dialysis.

Reports analyzing the histopathological differences between encapsulating peritoneal sclerosis (EPS) and simple peritoneal sclerosis (non-EPS) and those comparing the pathology of early and late EPS are limited. We present pathological comparisons between EPS and non-EPS, also between the early and late EPS stages. We compared peritoneal membrane (PM) samples (Group B) of 12 EPS patients (Group A) and 23 non-EPS cases regarding; mesothelial loss, submesothelial compact zone degenerated layer and compact zone thicknesses, densities of total and diseased vessels, fibrin stain, new membrane formation and degenerative changes. Group A was subdivided into 7 early (group A1) and 8 late (group A2) EPS cases; we compared both subgroups in the same manner and finally compared groups A1, A2, and B. No differences were found between groups A and B in the incidences of mesothelial detachment, new membrane formation and compact zone degenerative changes between the two groups. Furthermore, there were no differences in compact zone thickness, and vascular densities in the compact zone of respective vascular grade. Whereas, fibrin deposition and thickness of the submesothelial degenerated layer were significantly higher in group A than group B (P = 0.01 and 0.05, respectively), and the thickness of the compact zone was less in group A1 than in group A2 (P = 0.03). Positive fibrin stains and thick degenerative compact zone layers are important pathological findings in EPS. Angiogenesis, vasculopathy, new membrane formation, fibrosis and degenerative changes of the compact zone are not unique characteristics for EPS. Larger size studies are recommended to verify this issue.