Ultrasound-guided fine-needle aspirates are routinely used to confirm a diagnosis of HL in cats and to identify suppurative septic inflammation, some forms of neoplasia, and glycogen-like VH. However, definitive diagnosis of hepatic disease is otherwise impossible to achieve based only on liver aspirate evaluation because absence of acinar architecture compromises interpretation of anatomic lesion distribution and characterization.
Cytologic interpretation of liver aspirates is notoriously discordant with histologic features in biopsy specimens. Neither neoplasia nor sepsis can be definitively excluded with cytology, and inflammatory disease is too often suspected. Cytologic evaluation should not be the basis for recommending immunomodulatory or antifibrotic medications or longterm chelation therapy for copper-associated hepatopathy. Rather, liver biopsy remains the standard for diagnoses of most hepatic disorders.
Because most canine hepatocellular carcinomas are not characterized by dysplastic mitotically active hepatocytes, they are difficult to differentiate based only on cytologic aspiration. A differentiating histologic feature of these neoplastic lesions is atypical hepatic cord orientation and random dissecting arterioles, characteristics not discernible by evaluation of hepatic aspiration cytology.
