Fig. 3

Histological findings of NFMs in non-EPS patients. NFMs were observed microscopically in the peritoneal biopsies of non-EPS patients with peritoneal lavage treatment after completing PD. NFMs were attached to the peritoneal membrane proper and distinguished from the peritoneal membrane (PM) by the presence of exudative or fibrous features (a, c, e). The presence of an elastic fiber layer detected by elastic-Masson trichrome staining was helpful to distinguish the NFM from the PM because the elastic fiber layer was located in the upper part of PM but not in the NFM (a). Podoplanin immunostaining was helpful to identify the NFM and determine its histological stage. Podoplanin expression in fibroblast-like cells is characteristic of the NFM (b, d). Negative podoplanin expression in fibroblast-like cells indicates stage III NFM (scarring phase) (e, f). Absence of the original vascular structure including artery and vein complexes is another index of NFM (a, c, e). NFMs in non-EPS patients shifted to later histological stages: stage II (seven cases) and stage III (seven cases), compared with NFMs in EPS patients: stage I (five cases), stage II (two cases), and stage III (one case). a Elastic-Masson staining, ×200. c, e Masson staining, ×200. b, d, f IHC for podoplanin, ×200, bar = 100 μm