Case Studies
 

Biliary Cystadenoma in a 10-Month-Old Kitten and Its Successful Surgical Removal.

Biliary Cystadenoma: KEY

VETERINARIAN SPECIALTY CASE STUDY

The owners thought this young adult cat was just getting fat. After being treated for abdominal distension and constipation, X-rays helped shed light on the problem: Biliary Cystadenoma.

By Shawnon Kaiser, DVM
and Jason Balara, DVM
Diplomate American College of Veterinary Surgeons

Biliary Cystadenoma: 11. Referral

Gomez, a 10 month-old, male neutered, domestic medium hair cat, was referred to the Animal Specialty Group Emergency and Critical Care service for evaluation of a mid-abdominal mass that was discovered on radiographs (figures 1, 2) by the referring veterinarian.

Gomez had a history of 3-4 months of abdominal distension and weight gain and was undergoing treatment for constipation.

Biliary Cystadenoma: 2

Figures 1 and 2

2. Examination

On physical examination Gomez was bright and alert. Abdominal palpation revealed marked abdominal distension. The abdomen was soft and non-painful. His weight on presentation was 5.4 kg and his vital parameters were within normal limits. The remainder of his physical exam was unremarkable.

3. Diagnostics

An abdominal ultrasound revealed a large, lobulated, cystic structure within the abdominal cavity that appeared to be originating from a portion of the liver (figure 3). A PT/PTT was performed and was within normal limits.

Biliary Cystadenoma: 3

Figure 3

4. Treatment/Procedure

An exploratory laparotomy was performed and a large cystic structure arising from the distal margin of the right lateral liver lobe was identified. A partial hepatectomy was performed using a TA stapler across the distal quarter of the liver lobe and the structure was removed completely from the abdomen with no additional attachments seen (figure 4 and 5). The spleen had formed an incidental adhesion to the left lateral body wall. The remainder of the organs were unremarkable. The incision underwent a routine closure. The cystic structure was sent to the lab for histopathologic analysis. Anesthesia, surgery, and recovery were uneventful. The weight of the patient after cyst removal was 4.4 kg, indication a 1 kg weight loss.

5. Diagnosis

The pathology report identified a benign biliary cystadenoma lined by attenuated epithelial cells. Complete surgical removal was achieved with >5cm margins and should be curative.

Biliary Cystadenoma: 5

Figure 4

6. Discussion

Feline biliary cystadenoma are typically described as multifocal structures within the hepatic parenchyma many of which present with laboratory anomalies such as an increase in ALT or AST. These benign structures are most commonly reported in older animals (>11 years) but no apparent sex or breed predilection has been determined. As in this case, congenital type cysts in young animals may not present with systemic or laboratory abnormalities and the history may include abdominal distension. Large cystic structures with limited attachments to the liver in young animals are uncommon and few reports are available for review.

In younger animals this structure is presumptively congenital although the development of such structures are poorly understood, possibly arising from incomplete development of the biliary tree since microscopic evaluation of the epithelial lining is similar to that of the biliary tissue. Cysts are diagnosed based on the microscopic evaluation of a clear, fluid filled structure demonstrating an epithelial lining of simple cuboidal or attenuated cells. These lesions are typically benign although an ability of these tumors to become malignant has been described in humans. Structures removed should be sent for histopathologic evaluation and confirmation of complete removal.

Biliary Cystadenoma: 5-jar
Figure 5

A cyst that has ruptured causing free fluid within the abdomen may easily be mistaken for ascites due to other conditions. Evaluation of the fluid alone is not considered diagnostic as the lining of the capsule must be evaluated microscopically. Abdominal distension in kittens may be mistaken as secondary to effusion from parasitism or potentially FIP if fluid is readily palpable or if the structure has ruptured leaving free fluid in the abdomen. A thorough workup is required to differentiate a potential cystic mass.

Clinical presentation and history for these masses may include difficulty using the litter box or frequent urination if the structure becomes space occupying and places undue pressure on surrounding structures or causes organ displacement. In this case the patient was undergoing treatment for constipation which would be consistent with pressure being placed on the colon as the mass increased in size and explains why the treatments appeared to be progressively ineffective thus prompting radiographic evaluation.

Radiographs may demonstrate a cranial abdominal mass or space occupying lesion but are usually inadequate to define the type of structure or potential involvement of vital structures. Ultrasonographic evaluation is the preferred modality for better determining the structure and origin of the mass. Appearance of the tumor on ultrasound is classically hypoechoic when the structure is large, however smaller cyst structures may appear hyperechoic due to the echogenic wall structure and acoustic enhancement. Since malignant transformation has been described in humans, surgical removal is considered the treatment of choice. An exploratory laparotomy should be performed and removal of the entire cyst with >1cm margins (which may include the removal of an entire hepatic lobe) should be curative. Re-occurrence of cysts excised with adequate margins is extremely rare.

7. Recovery

Gomez spent one night in the hospital with supportive care and pain management prior to discharge from the hospital. The day after discharge the owner reported that he was doing great at home and appeared to be completely back to himself, including attempts to play with his sibling. His incision was rechecked two weeks post operatively and had healed without complication. No long term complications are anticipated.


REFERENCES: [1] Adler, R., Wilson, D.W.: 1995.  Biliary cystadenomas of cats.  Vet Path 32: 415-418; [2] Funk. 2002. Biliary cystadenoma in the Cat; [3] Nyland, T.G., Koblik, P.D., Tellyer, S.E.: 1999.  Ultrasonographic evaluation of biliary cystadenomas in cats.  Vet Radiology and Ultrasound  40: 300-306; [4] Trout, N.J.: 1997.  Surgical treatment of hepatobiliary cystadenomas in cats.  Seminars in Vet Med and Surg  12: 51-53; [5] Wallack. 2011. Abdominal ultrasonography of older cats: common findings and their significance (Proceedings)

Animal Specialty Group

DVM, Diplomate American College of Veterinary Surgeons

Dr. Jason Balara attended veterinary school at Tufts University, completed an internship at Angell Animal Medical Center, and finished his residency from both institutions. He believes in constantly improving the state of veterinary medicine, and passes on his wisdom by teaching students, interns, and residents alike.