Extrahepatic Cholangiocellular Carcinoma in a Cat

Abstract

Background: Primary hepatobiliary neoplasms (PHN) are uncommon seen structures in routine veterinary practice, representing only 1.5 to 2.3% of cats’ oncological cases. Among these, extrahepatic cholangiocellular carcinoma (ECC), also referred to as cholangiocarcinoma, is its most common malignant form. This neoplasm has an unknown etiology, with relevant metastatic potential and poor prognosis. Treatment options are limited to surgical excision with free margins and palliative treatment. The present report aims to describe an ECC case from a 14-year-old cat, where chosen treatment was surgical excision of the common bile duct with biliary diversion via cholecystoduodenostomy.

Case: A 14-year-old female, desexed mixed-breed feline patient was admitted with complaints of acute emesis and lethargy. Complementary diagnostic tests were requested, including a complete blood count, biochemical profile and abdominal ultrasonography (US). Clinical analysis revealed intensely icteric plasma and serum, reactive lymphocytes and “rouleaux” erythrocytes formation. Serum biochemistry showed high total plasma protein, alanine aminotransferase, alkaline phosphatase, gamma-glutamyl transferase and total bilirubin. US revealed a dilated gallbladder, intrahepatic bile ducts and common bile duct, the latter associated with an intraluminal structure in the distal portion. Surgical excision of the mass was performed via exploratory celiotomy, followed by cholecystoduodenostomy and histopathological analysis. Postoperative management included fluid therapy, ceftriaxone, methadone, dipyrone, dexamethasone, remifentanil; followed by the addition of Cerenia, mirtazapine, metoclopramide, glucose and norepinephrine. Histopathological examination revealed neoplastic cuboidal cells with scant eosinophilic cytoplasm, dense chromatin, fibroplasia, cellular pleomorphism, anisokaryosis, anisocytosis and the average of 5 mitotic figures in a 2.37 mm² area. These findings were consistent related do a ECC diagnosis. On the 5th day of hospitalization, the patient went into cardiorespiratory arrest unresponsive to cardiopulmonary resuscitation, and its demise was confirmed.

Discussion: Besides PHN are rare in small animal oncology, cholangiocarcinoma is the most common malignant neoplasm located on the biliary system in cats. Due to its rarity, and even its nonspecific clinical signs, it holds a peculiar challenge for veterinary diagnostic, often leading to be delayed and, frequently, worsening prognosis with high risk of metastasis. Definitive diagnosis is achieved only through histopathological examination. Treatment options are limited, primarily consisting in surgical excision with clean margins and palliative care, as there are scarce studies establishing both effective chemotherapy or radiotherapy protocols. Biliary diversion procedures, such as cholecystoduodenostomy, are frequently necessary. The prognosis for extrahepatic biliary obstruction, secondary to neoplasia requiring diversion, is unfavorable due to anesthetic and postoperative complications, resulting in a short survival time of 14 to 31 days. High-sensitivity imaging modalities, such as magnetic resonance imaging (MRI) and computed tomography (CT) are relevant for metastasis investigation, though their high costs, limiting factor for veterinarians in Brazil still remains. Further researches on this disease’s pathology and therapeutic protocols are essential to achieve better guides for veterinary professionals in future cases.

Keywords: oncology, neoplasia, cholangiocarcinoma, cholecystoduodenostomy.

Título: Carcinoma colangiocelular extra-hepático em uma gata

Descritores: oncologia, neoplasia, colangiocarcinoma, colecistoduodenostomia.