title: Ossification of the peritoneal membrane.
abstract: BACKGROUND
  Peritoneal dialysis (PD) patients rarely develop sclerosing peritonitis (SP), a severe, life-threatening condition of unknown pathogenesis. Ossification of the peritoneum (PO) is a rare occurrence, which has, however, been reported in PD patients with SP.
  
  
  OBJECTIVE
  To investigate etiopathogenetic correlations between PO and SP by histopathological examination.
  
  
  METHODS
  We examined biopsy specimens, obtained by laparoscopy or during surgery from 36 patients with SP, from all parts of Italy in the past 8 years for evidence of peritoneal calcification or ossification. Other studies were performed on a sample of dense white material found under the parietal peritoneum of 1 patient during laparoscopy.
  
  
  RESULTS
  Ossification of the peritoneum was found in 4/16 patients with calcifications. In addition to PO, we also found bone marrow in two specimens and arterial ossification in one case. In specimens with calcifications, and especially those with ossification, there was evidence of peritoneal inflammation with infiltration of lymphocytes, multinuclear giant cells, macrophages, and mast cells. The chemical composition of the whitish material was 85% calcium chloride and 15% hydroxyapatite.
  
  
  CONCLUSIONS
  Calcifications alone were found in 33% (12/36) of cases of SP; 11% of SP cases were complicated by both peritoneal calcification and ossification (4/36), which indicates great availability of calcium under conditions of inflammation. Where does this calcium come from? In 1 patient with PO, the quantity of calcium was enormous and its unusual composition suggested a link with the calcium contained in dialysis solution.
authors.affiliation: Department of Nephrology and Dialysis, University Hospital, Siena, Italy. N.DiPaolo@ao-siena.toscana.it
authors.forename: Nicola
authors.initials: N
authors.lastname: Di Paolo
authors.forename: Giovanni
authors.initials: G
authors.lastname: Sacchi
authors.forename: Paola
authors.initials: P
authors.lastname: Lorenzoni
authors.forename: Enrico
authors.initials: E
authors.lastname: Sansoni
authors.forename: Enzo
authors.initials: E
authors.lastname: Gaggiotti
mesh_terms: D000328:Adult; D001706:Biopsy; D002114:Calcinosis / Q000209:etiology / Q000473:pathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009999:Ossification, Heterotopic / Q000209:etiology / Q000473:pathology*; D010530:Peritoneal Dialysis / Q000009:adverse effects; D010532:Peritoneal Diseases / Q000209:etiology / Q000473:pathology*