Diagnostic comparison of needle and wedge biopsy specimens of the liver in dogs and cats.

OBJECTIVE: To compare morphologic diagnoses determined from needle biopsy specimens obtained from the livers of dogs and cats with morphologic diagnoses determined from wedge biopsy specimens.
DESIGN: Prospective study. ANIMALS: 124 dogs and cats. PROCEDURE: 2 needle biopsy specimens were obtained from each animal; wedge biopsy specimens were obtained from the same liver lobe during laparotomy or postmortem examination. Histologic features were scored independently by 3 individuals; a morphologic diagnosis was rendered after histologic features were scored. Cases were included only if at least 2 of the 3 examiners agreed on the morphologic diagnosis; the definitive diagnosis was considered to be the morphologic diagnosis rendered for the wedge biopsy specimen. Physical characteristics (length, width, surface area, degree of fragmentation, and number of portal triads for needle biopsy specimens and surface area for wedge biopsy specimens) were determined.
RESULTS: Definitive diagnoses included hepatic necrosis (n = 10), cholangitis-cholangiohepatitis (13), chronic hepatitis-cirrhosis (12), canine vacuolar hepatopathy (11), portosystemic vascular anomaly-microvascular dysplasia (17), neoplasia (10), miscellaneous hepatic disorders (18), and no hepatic disease (33). For individual examiners, the morphologic diagnosis assigned to needle biopsy specimens agreed with the morphologic diagnosis assigned to wedge biopsy specimens for 56 and 67% of the specimens. All 3 examiners agreed on the morphologic diagnosis assigned to needle and wedge biopsy specimens for 44 and 65% of the specimens, respectively. Morphologic diagnoses assigned to needle biopsy specimens concurred with the definitive diagnosis for 59 of 124 (48%) animals. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that needle biopsy specimens of the liver from dogs and cats must be interpreted with caution.