Sclerosing encapsulating peritonitis in a dog with pancreatic ductal adenocarcinoma

BACKGROUND: Sclerosing encapsulating peritonitis (SEP) is a rare clinical syndrome characterised by fibrosis and thickening of the peritoneum with massive adhesions of the abdominal organs. In humans, abdominal tumours, such as pancreatic adenocarcinoma, can be underlying diseases of SEP. This report describes a case of SEP in a dog with pancreatic ductal adenocarcinoma. CASE PRESENTATION: An 11-year-old male neutered French Bulldog presented with chronic vomiting. Ultrasonography revealed a mass in the centre of the abdomen. A small amount of ascites, interpreted as modified transudate, was present in the abdominal cavity. Computed tomography (CT) revealed peritoneal effusion with a thickened peritonium. Laparoscopy revealed a large nodular lesion occupying the central portion of the abdomen, continuous with the falciform ligament. Histological examination of the biopsy specimens of the mass, abdominal wall, and gastric peritoneum revealed marked fibroplasia with mild lymphoplasmacytic infiltrates. Based on these results, a tentative diagnosis of early stage sclerosing encapsulating peritonitis (SEP) was made. Prednisolone and tamoxifen were administered with the expectation of ameliorating SEP, however, the dog died 61 days post diagnosis. At autopsy, the intestinal loop and mesentery were encased in the fibrous membrane, which is a typical finding in SEP. Histopathology and immunohistochemistry of the samples obtained at autopsy supported the diagnosis of pancreatic ductal adenocarcinoma with peritoneal dissemination and distant metastasis with desmoplasia. The unexpectedly hardened skin, where previously laparoscopic ports were inserted, histologically contained the same carcinoma cells with desmoplasia. CONCLUSIONS: To the best of our knowledge, this is the first report of canine SEP with pancreatic ductal adenocarcinoma that also caused metastasis to port insertion sites as well as distant organs.