Liver Biopsies in Dogs Undergoing Splenectomy

In the Literature

Clarke E, Levien AS, Bennett RA, Perry S, Daniel G. Clinical utility of liver biopsies in dogs undergoing splenectomy. J Small Anim Pract. 2020;61:684-688.

The Research …

During laparotomy to remove an abdominal mass, the remainder of the abdomen should be explored, and relevant ancillary tissue should be sampled for histologic assessment and clinical staging. Results can have significant prognostic potential and inform decisions on whether to pursue postsurgical adjuvant therapy; however, what constitutes relevant ancillary tissue is not firmly established for many disease processes. Preoperative imaging (eg, ultrasonography) and surgeon assessment of gross abdominal structures often guide the decision to obtain additional tissue samples during surgery. 

This retrospective study reviewed medical records of dogs that underwent liver biopsies concurrent with splenectomy for histologically undiagnosed splenic masses. The goal was to determine the use of routine liver biopsies in grossly normal-appearing livers. Routine liver biopsy was the standard surgical practice, regardless of gross liver appearance; surgeon bias was thus not a consideration during decision-making.

Of 113 splenic masses, 44.2% were malignant; a minority (18.5%) of liver biopsies confirmed concurrent hepatic malignancy. During preoperative imaging, 10 out of 70 (14.3%) dogs with ultrasonographically normal livers and 11 out of 27 (40.7%) dogs with abnormal livers were confirmed to have malignancy on biopsy. 

Based on gross appearance of the liver at surgery, 1 out of 40 (2.5%) dogs with grossly normal livers and 20 of 69 (29.0%) dogs with grossly abnormal livers were confirmed to have malignant hepatic conditions. Although ultrasonographically abnormal livers were ≈16 times more likely to have malignancy confirmed via biopsy, <50% of ultrasonographically abnormal livers represented malignant tumors. Applying standard accuracy assessments to these data, ultrasonography is 79% specific for malignancy but only 52% sensitive.¹ The study did not discern the types of abnormalities noted, which could help further refine the predictive potential of ultrasonography.

These data suggest that routine biopsy of grossly normal-appearing livers may be unwarranted and is a low-yield procedure. Although grossly abnormal-appearing livers were ≈16 times more likely to represent malignant disease, two-thirds still represented benign disease in this setting. Applying standard accuracy assessments, gross appearance is 95% sensitive but is only 44% specific for malignant disease.¹

… The Takeaways

Key pearls to put into practice:

• Utility of presurgical ultrasonography to differentiate benign from malignant liver involvement concurrent with a splenic mass is low and should not be used alone when deciding to pursue exploratory surgery.

• In dogs with concurrent splenic masses, the gross appearance of the liver at surgery does not adequately discriminate between benign and malignant disease and, therefore, this appearance should not be used to make major clinical decisions (eg, euthanasia at time of surgery).

• Grossly abnormal-appearing livers should be biopsied in patients undergoing splenectomy for undiagnosed splenic masses; however, the cost:benefit ratio and diagnostic yield in normal-appearing livers are low.