Little has been written over the years describing feline hepatocellular carcinoma (HCA). The estimated prevalence ranges from 1 to 3% of all feline cancers; primary hepatic tumors are uncommon in the cat. Compared to dogs, cats have a lower risk for HCA and that fact also goes along for metastatic liver cancer in cats. While there is an association between viral infections and HCA in humans (hepatitis B and C), no evidence has been shown for a viral association in cats.
Because so little has been characterized about feline HCA, the authors performed this retrospective study of 19 cats describing the signalment, clinical features, clinicopathologic parameters, imaging characteristics, hepatic mass size and lobe distribution, concurrent disorders and survival times. Cats developing hepatobiliary tumors often have the big three nonspecific clinical signs of illness: anorexia, lethargy, and weakness. There may be an association with increased hepatic transaminase activities, yet cats will more likely demonstrate hyperbilirubinemia because biliary carcinomas commonly cause cholestatic jaundice.
Of the 19 cats, the median age was 14 years of age with a mix of breed disposition plus no significant gender predisposition noted. The one most common co-existent disease noted was hyperthyroidism though most of the cats had one of more co-existent or pre-existent conditions. Two cases were noted to have increased copper accumulations in the liver tissue. Along with the clinical signs described earlier, the most commonly increased liver enzyme was AST in >90% of the cats, increased ALT and ALP were seen in >71%, and hyperbilirubinemia in >38% of the cats with HCA. Hepatic masses were only palpated in 21% of the cats. Thoracic radiographs were available for 14 cats and a hepatic mass was suspected in only one cat. Of 14 cats undergoing abdominal ultrasonography, localized lesions were found in most of the cats except hepatic masses were not detected in three cats (21%). The distribution of the tumors was nearly equal between right and left liver lobes, and 2 cats had HCA in multiple lobes. The median survival time of eight of ten cats diagnosed antemortem and not euthanized was 1.4 yr. Six cats underwent complete HCA resection and their median survival time was 2.4 yr. Metastatic HCA was not noted in any cat, even in examination of regional hepatic lymph nodes. Cytologic examination of aspirates or imprint samples from HCA frequently failed to diagnose neoplasia, leaving tissue biopsy with histopathology as the gold standard for definitive diagnosis of the disease.
In conclusion, diagnosis of feline HCA was not reliable with the use of clinical signs, clinical pathology, cytology or imaging studies. Concurrent disease often further obscured the diagnosis. HCA is a rare neoplasm affecting geriatric cats. By its nature, the neoplasm seems slow to metastasize, expands locally into surrounding liver tissue, and surgical resection offered effective palliation treatment for six cats in this study. Even though the cats in this instance were elderly, surgical resection resulted in the cats exhibiting an improved well-being and survival times of 1 to 6.5 yr. (VLT)