Case report: Sclerosing encapsulating peritonitis in a cat with disseminated pancreatic adenocarcinoma of presumed ductal origin

A 9-year-old, neutered male, domestic short-haired cat was referred for recurrent ascites of unknown etiology over a week. Physical examination revealed abdominal distension and ultrasonography revealed a large volume of ascites throughout the abdominal cavity; this was interpreted as modified transudate. The mesentery and abdominal fat were hyperechoic and edematous. Fat tissue was assessed using fine-needle aspiration cytology, and adipocytes, fat-phagocytizing macrophages, and neutrophils were identified. Computed tomography revealed a pancreatic mass connected to the left pancreatic leg. Exploratory laparoscopy confirmed nodular masses and organ adhesions, leading to a tentative diagnosis of sclerosing encapsulating peritonitis. The cat was administered prednisolone, vitamin E, and tamoxifen but died 22 days after the initial therapy. Necropsy revealed a multi-lobulated pancreatic tumor (10 × 10 cm) tightly attached to the stomach and intestine, with a large amount of ascites. The peritoneum, stomach, intestine, and mesentery were covered with numerous disseminated nodules of various sizes (1-5 mm diameter). Microscopically, the tumor consisted of extensive adipose tissue, locally extensive inflammatory infiltrates, fibrous connective tissue, and small invasive proliferative glands. Well-defined small irregular glands composed of single-layered epithelial cells that appear to be of ductal origin were surrounded by an abundant desmoplastic stroma. Neoplastic nodules were widespread in the liver, stomach, peritoneum, mesentery, mesenteric lymph nodes, lungs, and urinary bladder. Immunohistochemistry revealed that the neoplastic glands were positive for pan-cytokeratin, confirming the pancreatic epithelial origin of the tumor. This is the first report of sclerosing encapsulating peritonitis accompanied by aggressive pancreatic adenocarcinoma of presumed ductal origin and extensive metastasis in a cat.

Successful treatment of sclerosing encapsulating peritonitis in a cat using bioresorbable hyaluronate-carboxymethylcellulose membrane after surgical adhesiolysis and long-term prednisolone

Case summary

An 8-year-old neutered male domestic shorthair indoor cat was presented with an 8-week history of intermittent vomiting, anorexia and weight loss that had been unresponsive to supportive treatment. Abdominal ultrasound revealed plication of the small intestine and fluid accumulation proximal to the lesion, and a linear foreign body was suspected. An exploratory celiotomy showed cocoon-like encapsulation of the entire intestine. Surgical adhesiolysis and full-thickness biopsy were performed, and histopathologic examination revealed mild thickening of the visceral peritoneum with fibrin deposition, as well as mild neutrophil and lymphocyte infiltration. These findings were compatible with sclerosing encapsulating peritonitis (SEP). The cat recovered well postoperatively and was discharged the next day. Prednisolone was administered for 7 weeks to prevent recurrence of SEP. Five months after surgery, the cat was re-presented with anorexia and chronic vomiting. Based on the clinical examination findings, recurrent SEP was suspected. At the second surgery, surgical adhesiolysis was repeated and a bioresorbable hyaluronate-carboxymethylcellulose membrane was used to cover the serosal surface and thus prevent adhesion formation. Histopathologic findings of the peritoneal biopsy specimen confirmed SEP. Long-term prednisolone treatment (1 mg/kg for the first dose and 0.5 mg/kg every 48 h for maintenance) was administered postoperatively. The cat survived for more than 1239 days without recurrence.

Relevance and novel information

To our knowledge, this is the first report of SEP in a cat with long-term survival. The use of a bioresorbable hyaluronate-carboxymethylcellulose membrane and long-term prednisolone treatment may have prevented short-term and long-term recurrence, respectively, in this case.

Sclerosing encapsulating peritonitis in cats: a two-case report and literature review

Case series summary

Two castrated male domestic shorthair cats (aged 8 months [case 1] and 13 years [case 2]) were presented at the Small Animal Clinic of the Veterinary Medicine University of Vienna, Austria, both with acute vomiting and distended abdomen, as well as a history of chronic apathy, recurrent vomiting and diarrhoea. Both cats underwent invasive diagnostic procedures approximately 1 month before the diagnosis of sclerosing encapsulating peritonitis (SEP), namely an exploratory laparotomy and a bronchoscopy, respectively. Abdominal ultrasound revealed severely corrugated intestinal loops and, in case 2, the presence of peritoneal effusion. A thick and diffuse fibrous capsule around the intestine was detected and removed surgically, and biopsies were taken from the affected organs confirming the SEP. Case 1 recovered well, was discharged some days after surgery and was clinically unremarkable for the next 2 years. Case 2 showed unsatisfactory improvement directly after surgery and was euthanased a few days later, as the owner declined any further therapy.

Relevance and novel information

SEP is a very rare condition of unclear origins in cats. Here we describe the clinical and diagnostic imaging features, surgical treatment, and outcome of SEP in two cats. The results indicate that prompt diagnosis and appropriate interventions may improve the outcome.

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.

Imaging Findings in Dogs and Cats With Presumptive Sclerosing Encapsulating Peritonitis

This retrospective case series describes imaging findings in seven dogs and two cats with a presumptive diagnosis of sclerosing encapsulating peritonitis (SEP) between 2014 and 2021. Peritoneal effusion was present in all animal patients. Sonographically, echogenic fluid with or without echogenic intraperitoneal septations, gathered or corrugated bowel loops, and abdominal lymphadenomegaly were suggesting an inflammatory process and the presence of adhesions. Gathering of the bowel with abdominal distension and/or signs of intestinal obstruction were major findings on radiographs. Abdominal fat stranding was an additional finding in animals undergoing a CT examination. Previous surgery, pregnancy, and the presence of a perforating foreign body were potential predisposing causes in 4/9 animals. Peritonitis was septic in 4/9 animals. As SEP is a rare condition but life threatening, this detailed description of imaging findings in a short case series can be useful for a presumptive diagnosis and surgical planning.

Laparoscopic ovariectomy in a dog with type III sclerosing encapsulating peritonitis and literature review

Sclerosing encapsulating peritonitis is a rare and not well-recognized disease in veterinary medicine. A 14-month-old female intact mixed-breed dog was diagnosed with sclerosing encapsulating peritonitis (SEP) at the age of 5 months after a routine work-up including biopsies from an exploratory laparotomy. Symptomatic treatment with an immunosuppressive dose of prednisolone was started, but dose reduction was unsuccessful. Combined treatment with tamoxifen, a selective estrogen receptor modulator used for its TGF-β1 suppression of fibroblasts was discussed; the owner was informed about the risk for developing a pyometra. About one year later the owner wanted to spay her dog and an ovariectomy was recommended, especially due to the extensive adhesions. A laparoscopic approach was chosen to reduce the amount of intraoperative tissue manipulation and inflammation, as well as to minimize the size of the incision. The dog continues to be doing well one year after surgery and prednisolone could be reduced to a low maintenance dose after surgery; so far, the addition of tamoxifen was not required. In selected cases, laparoscopy appears as a safe alternative in patients with adhesions, but the surgeon should always be prepared to convert in case of impaired vision, especially in the absence of tactile sensation. This case report is the first description of laparoscopy in a dog with SEP. Laparoscopy may serve as an easily accomplished minimally invasive method to diagnose SEP, but further studies are required.

Pyloric outflow obstruction secondary to sclerosing encapsulating peritonitis in a dog

A 6-year-old, male neutered mixed breed dog was presented emergently with a three-week history of hyporexia, vomiting, diarrhoea and weight loss. Upon examination, the patient was dull, had generalised muscle atrophy, moderate abdominal pain and a mild amount of peritoneal effusion. A fluid-filled, distended, corrugated small bowel with marked gastroparesis and moderate peritoneal effusion was noted on abdominal ultrasonography. Endoscopy revealed hyperaemic and friable mucosa and a subjectively narrowed pylorus. Emergency exploratory celiotomy was performed due to worsening patient condition and revealed thick, diffuse, fibrous adhesions of the abdominal cavity. Based on these findings, sclerosing encapsulating peritonitis (SEP) was suspected. A large mass of omentum adjacent to the greater curvature of the stomach had caused a pyloric outflow obstruction. Adhesiolysis was attempted but was unsuccessful due to the friability of the small intestines. The dog was humanely euthanased under anaesthesia. A diagnosis of SEP was confirmed via necropsy. No underlying cause was identified. This is the first known case of a pyloric outflow obstruction secondary to SEP in a dog. Although rare, this condition should be considered as a differential for dogs with signs of a pyloric outflow obstruction with concurrent ascites and abdominal pain, hyporexia, vomiting and diarrhoea.

IMAGING DIAGNOSIS-SCLEROSING ENCAPSULATING PERITONITIS IN A DOG

An approximately 5-month-old American Staffordshire terrier was presented with a history of recurrent peritoneal effusion. Abdominal radiographs and ultrasound showed a loculated effusion in the ventral abdomen with dorsal displacement of abdominal organs, hepatomegaly and rounding of liver and splenic margins. Computed tomography demonstrated centrally located gastrointestinal segments surrounded by a thin soft tissue band and a thickened peritoneal lining. At necropsy a fibrous membrane continuous with liver and splenic capsules encapsulated all abdominal organs. Microscopically the abdominal wall and fibrous capsule consisted of an irregular thick layer of hypocellular connective tissue. The final diagnosis was sclerosing encapsulating peritonitis.