What Is Your Diagnosis?

Katherine Barnes Department of Small Animal Clinical Sciences, Virginia-Maryland College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061.

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History

A 13-year-old spayed female Fox Terrier was evaluated because of a several-day history of vomiting, decreased appetite, and an enlarged abdomen. On physical examination, the patient was lethargic, with generalized muscle atrophy, slightly pale mucous membranes, and a distended and turgid abdomen. A CBC revealed regenerative anemia (Hct, 34.8% [reference range, 42.7% to 61.9%]; reticulocyte count, 136.9 × 109 reticulocytes/L [reference range, 13.3 × 109 reticulocytes/L to 95.9 × 109 reticulocytes/L]) and thrombocytosis (platelet count, 1,083 × 103 platelets/μL; reference range, 150 × 103 platelets/μL to 393 × 103 platelets/μL). Serum biochemical analysis revealed mild azotemia (BUN concentration, 61 mg/dL [reference range, 9 to 30 mg/dL]; creatinine concentration, 1.4 mg/dL [reference range, 0.7 to 1.3 mg/dL]), hyperphosphatemia (8.0 mg/dL; reference range, 1.9 to 4.4 mg/dL), hypoalbuminemia (2.5 g/dL; reference range, 2.8 to 3.7 g/dL), high liver enzyme activities (alanine aminotransferase, 259 U/L [reference range, 16 to 75 U/L]; aspartate transaminase, 52 U/L [reference range, 13 to 48 U/L]; alkaline phosphatase, 759 U/L [reference range, 8 to 70 U/L]; γ-glutamyltransferase, 6 U/L [reference range, 1 to 5 U/L]), hypochloremia (107 mEq/L; reference range, 110 to 119 mEq/L), hyponatremia (142 mEq/L; reference range, 143 to 152 mEq/L), and hyperkalemia (5.9 mEq/L; reference range, 3.4 to 4.5 mEq/L). Coagulation values (prothrombin time and partial thromboplastin time) were within reference range. Abdominocentesis revealed a serosanguineous effusion without evidence of infectious agents or foreign material. Abdominal CT was performed (Figure 1).

Figure 1—
Figure 1—

Transverse (A) and dorsal (B) CT images (soft tissue algorithm; window width, 400 Hounsfield units [HU]; window level, 40 HU; slice thickness, 1.0 mm) from a continuous sequence of the abdomen of a 13-year-old spayed female Fox Terrier that was referred for vomiting, decreased appetite, and an enlarged abdomen. Images were obtained immediately after IV administration of an iodinated contrast agent. L = Left. R = Right.

Citation: Journal of the American Veterinary Medical Association 247, 1; 10.2460/javma.247.1.43

Determine whether additional imaging studies are required, or make your diagnosis from Figure 1—then turn the page →

Figure 2—
Figure 2—

Same CT images as in Figure 1. Note the peritoneal effusion (black arrows), small intestines surrounded by a soft tissue capsule (white arrows), and partially mineralized mass (asterisks). The compartmentalized and encapsulated appearance of the small intestines is consistent with sclerosing encapsulating peritonitis.

Citation: Journal of the American Veterinary Medical Association 247, 1; 10.2460/javma.247.1.43

Diagnostic Imaging Findings and Interpretation

There is a 10 × 10-cm peripherally enhancing and centrally hypoattenuating mass appearing to originate from the right side of the liver and extending to the level of the fourth lumbar vertebra (Figure 2). An irregular area of mineralization in the cranioventral aspect of the mass is apparent. This mineralized area was also visualized on images prior to IV contrast administration (not shown). The small intestinal tract appears confined within a soft tissue capsule and located in the left side of the abdomen. Both kidneys are displaced dorsally, and there is a moderate amount of peritoneal effusion present. The large mass associated with the liver is suggestive of neoplasia; however, other differential diagnoses (eg, abscess, hematoma, or granuloma) cannot be ruled out on the basis of imaging alone. The abdominal fluid and encapsulation of abdominal organs are suggestive of sclerosing encapsulating peritonitis (SEP).1–3

Treatment and Outcomes

The patient underwent exploratory celiotomy. A thick fibrous capsule was found overlying the entirety of the abdominal contents with the exception of the urinary bladder. An incision was made into the capsule and a large amount of serosanguineous abdominal fluid was removed by suction. Once the fibrous capsule was opened, the rest of the abdominal organs appeared to be compartmentalized within several separate cocoonlike coverings. The mass was found in the right side of the abdominal cavity and also appeared encased in a thick fibrous tissue covering. The stalk was ligated with size-0 silk suture and the mass removed. Several biopsy specimens of adhesions were also obtained; however, most adhesions could not be broken down without damage to underlying organs. Histologic evaluation of the mass indicated hepatocellular carcinoma with multiple areas of hemorrhage and necrosis. Histologic evaluation of the adhesions revealed granulation tissue, fibrinous peritonitis, and chronic hemorrhage (consistent with a diagnosis of SEP).1–3

The patient remained stable after surgery and was discharged from the hospital several days later. The dog began a treatment course of prednisone and tamoxifen after consultation with an oncologist.

Comments

Sclerosing encapsulating peritonitis is a rare disease of dogs in which severe inflammation results in encasement of the abdominal organs within thick layers of collagenous connective tissue.3 Although a definitive diagnosis is made through microscopic analysis of adhesions, a presumptive diagnosis of SEP can be made on the basis of findings on abdominal imaging. In humans with SEP, the most common CT findings include mineralization of the peritoneal membrane, thickening of the peritoneal membrane, intestinal wall thickening, intestinal tethering, loculation of peritoneal effusion, and intestinal dilation.4 Computed tomographic evaluation of canine patients with SEP has not yet been reported. Other imaging modalities (eg, ultrasonography) have been used to diagnose changes associated with SEP; however, CT provides a more comprehensive picture for evaluation of the abdomen.5

In dogs, the severe inflammation associated with SEP has been linked to several underlying diseases including steatitis, fiberglass ingestion, bacterial peritonitis, leishmaniasis, and mesothelioma.1,6 In humans, SEP has been associated with administration of β-adrenergic receptor antagonists (beta blockers), peritoneal dialysis, peritoneal venous shunts, blunt abdominal trauma, asbestos, carcinoid syndrome, and recurrent polyserositis (familial Mediterranean fever).3 To the knowledge of this author, hepatocellular carcinoma has not been previously associated with SEP in any species. However, it is possible that the tumor may have contributed to (or initiated) this condition as no other inciting cause could be found. One possible explanation for this relationship is repeated hemorrhage and necrosis of the hepatocellular carcinoma (which was supported by histologic findings) leading to a chronic inflammatory state and subsequent development of SEP.

Prior to histologic confirmation, appearance of the mass on CT scans was suggestive of a hepatic tumor because of its location in the cranial aspect of the abdomen, size, and enhancement pattern in the arterial phase.7 Visualization of a mass on preoperative imaging allowed identification of a potential source of chronic inflammation and the opportunity to target treatment. Preoperative imaging additionally proved essential in the dog of the present report as the thick adhesions surrounding the abdominal contents would have made identification of the mass during surgery much more difficult.

Presence of abundant peritoneal effusion on abdominal imaging is a common finding in instances of SEP.3,5 The underlying cause of peritoneal effusion associated with SEP is likely multifactorial and includes vasculitis, immature collagen in vessels, lymphatic obstruction, portal hypertension, or concurrent biliary disease.1 Results of cytologic evaluation of the effusion are usually consistent with mixed inflammatory cells, erythrophagia (indicating chronic hemorrhage), reactive mesothelial cells, and fibroblasts.3 Many of the hematologic findings found on CBC and serum biochemical analysis in the dog of the present report (eg, the electrolyte abnormalities, hypoalbuminemia, and anemia seen) may be explained by the presence of this hemorrhagic and inflammatory effusion.

Treatment for SEP, regardless of the underlying cause, includes medications to slow formation of adhesions and decrease peritoneal effusion. In this case, surgery was performed to remove the mass identified on CT scan and to obtain biopsy samples of adhesions (to confirm the diagnosis of SEP). Treatment was then initiated with corticosteroids and tamoxifen. Corticosteroids have been used to slow the progression of disease by way of decreasing fibrous tissue formation and blunting the inflammatory response. Tamoxifen is a nonsteroidal antiestrogen drug that has been used in conjunction with surgery to successfully control a case of SEP in a German Shepherd Dog.2 This medication promotes degradation of collagen through production of transforming growth factor-β and synthesis of metalloproteinase. Serial abdominal imaging studies (eg, ultrasonography) can then be used to monitor progression of disease. Surgery to remove the compartmentalizing adhesions, open fluid pockets, and remove necrotic organs is often indicated in humans. However, surgery to remove adhesions in canine patients is largely unsuccessful and has led to multiple intestinal perforations and subsequent euthanasia.1

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  • 2. Etchepareborde S, Heimann M, Cohen-Solal A, et al. Use of tamoxifen in a German Shepherd Dog with sclerosing encapsulating peritonitis. J Small Anim Pract 2010; 51: 649653.

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  • 3. Hardie EM, Rottman JB, Levy JK. Sclerosing encapsulating peritonitis in four dogs and a cat. Vet Surg 1994; 23: 107114.

  • 4. George C, Al-Zwae K, Nair S, et al. Computed tomography appearances of sclerosing encapsulating peritonitis. Clin Radiol 2007; 62: 732737.

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  • 5. Ti JP, Al-Aradi A, Conlon PJ, et al. Imaging features of encapsulating peritoneal sclerosis in continuous ambulatory peritoneal dialysis patients. AJR Am J Roentgenol 2010; 195:W50W54.

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  • 6. Geninet C, Bernex F, Rakotovao F, et al. Sclerosing peritoneal mesothelioma in a dog—a case report. J Vet Med A Physiol Pathol Clin Med 2003; 50: 402405.

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  • 7. Fukushima K, Kanemoto H, Ohno K, et al. CT characteristics of primary hepatic mass lesions in dogs. Vet Radiol Ultrasound 2012; 53: 252257.

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