CAN THE NEUTROPHIL COUNT FROM HEPATIC FINE NEEDLE ASPIRATE CYTOLOGY BE USED TO DIAGNOSE HEPATITIS IN DOGS? - A PILOT STUDY

Abstract

Background: Cytological diagnosis of inflammation on canine hepatic aspirates can be confounded by neutrophilic infiltrates in the liver of dogs with nodular regeneration, by extra-medullary hematopoiesis, and by marked blood contamination. Objectives: Assess the association between neutrophil counts on canine hepatic cytology and histopathological diagnoses of hepatitis and non-inflammatory hepatopathy. Determine a cut-off value for cytological diagnosis of hepatitis. Methods: Retrospective blinded pilot study. Three observers independently reviewed hepatic aspirates, which had corresponding histopathological examination performed within 2 days. Number of neutrophils per 200 hepatocytes was determined and averaged between observers. Only neutrophils within or directly in contact with a cluster of 5 hepatocytes were counted, and only intact hepatocytes within an approximate monolayer were included. Data are presented as median [range], and the Mann Whitney U test used to compare between groups. Results: Eighteen cases were included (13 hepatitis and 5 vacuolar hepatopathy). Aspirates with a histopathological diagnosis of hepatitis had increased numbers of neutrophils compared to vacuolar hepatopathy (7.7 [0.3-18.3] vs 3.0 [1.0-5.3]; p=0.038). ROC analysis indicated that 6 neutrophils was 61.5% (CI 31.6-86.1%) sensitive and 100% (CI 47.8-100%) specific for identifying hepatitis. Conclusions: Liver aspirates from hepatitis cases have a higher number of neutrophils on cytology compared with vacuolar hepatopathy; however, larger studies including dogs with other liver pathologies are required. Identification of 6 or more neutrophils per 200 hepatocytes may be highly suggestive of hepatitis.