Postmortem diagnosis of exocrine pancreatic adenocarcinoma mimicking encapsulating peritoneal sclerosis in a cat: Clinical and histopathological insights.

Kosuke Kobayashi ,  Yuga Kawabata ,  Sho Kadekaru ,  Osamu Sakai ,  Ryohei Yoshitake ,  Yohei Mochizuki , Shin-Ichi Nakamura ,  Kenji Kutara

BACKGROUND: Encapsulating peritoneal sclerosis (EPS) is a rare clinical syndrome, either idiopathic or secondary to abdominal inflammation, characterized by fibrotic thickening of the peritoneum that encases the abdominal organs. Herein, we describe a case involving a relatively young cat initially suspected of having EPS based on clinical imaging findings, but ultimately diagnosed postmortem with peritoneal dissemination of exocrine pancreatic adenocarcinoma. CASE DESCRIPTION: A 2-year-old castrated male domestic shorthair cat presented with abdominal distension and anorexia. The blood test results revealed no significant abnormalities. Imaging revealed severe ascites, digestive tract consolidation, pancreatic enlargement, and irregular peritoneal thickening with nodules. The ascitic fluid was negative for the feline coronavirus gene, and no increase in anti-feline coronavirus antibody titer was found in the blood. Given the patient's age, neoplastic disease was considered unlikely, and EPS was suspected based on the imaging findings. Despite receiving medical treatment with prednisolone, the cat died 19 days later. Postmortem examination revealed an exocrine pancreatic adenocarcinoma with abdominal and lung metastases. The peritoneal tissue formed a mass within the tumor, encapsulated the upper small intestine, caused ileus, and exhibited severe fibrosis. The cat was diagnosed with cancerous peritonitis, mimicking EPS based on histopathological findings. CONCLUSION: In the present case, peritoneal dissemination of exocrine pancreatic adenocarcinoma resulted in encapsulation of the gastrointestinal tract by thickened peritoneal tissue, producing clinical features that closely resembled EPS. Although antemortem diagnosis was challenging in this case, malignancy should be considered in the differential diagnosis when EPS is suspected. In addition, the possibility of neoplasia should be carefully considered, even in relatively young cats.

Open Veterinary Journal

15

8

3904

3911

10.5455/OVJ.2025.v15.i8.57

41036019