Characterization of blue-green blood leukocyte inclusions and accompanying clinical, hematologic, and serum biochemical changes in dogs

Kimberley N Sebastian; Cynthia A Lucidi; Michael A Scott

doi:10.1111/vcp.13348

Characterization of blue-green blood leukocyte inclusions and accompanying clinical, hematologic, and serum biochemical changes in dogs

Vet Clin Pathol. 2024 Apr 3. doi: 10.1111/vcp.13348. Online ahead of print.

Authors

Kimberley N Sebastian¹, Cynthia A Lucidi², Michael A Scott¹

Affiliations

¹ Department of Pathobiology and Diagnostic Investigation, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan, USA.
² Veterinary Diagnostic Laboratory, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan, USA.

PMID: 38570895
DOI: 10.1111/vcp.13348

Abstract

Background: Lipofuscin-like cytoplasmic inclusions have been reported in human blood neutrophils and monocytes but have not been described in dogs. In people, these "green granules of death" have been associated with moderate to severe hepatocellular injury and high mortality.

Objectives: To describe clinicopathologic abnormalities, diagnoses, and outcomes of dogs with greenish inclusions in blood neutrophils or monocytes, and to determine if the inclusions have features of lipofuscin.

Methods: Clinical cases were identified prospectively through routine evaluation of CBC samples. Leukocyte inclusions were characterized with routine staining and assessed for iron and autofluorescence. Additional cases were identified by examination of archived blood smears from dogs meeting search criteria for hepatocellular injury, and clinicopathologic findings were recorded.

Results: All 7 prospectively identified dogs with inclusions had inflammation and moderate to marked increases in serum alanine aminotransferase (ALT) activity, as did the 4 dogs identified from the 97 meeting retrospective search criteria. The inclusions were Prussian blue-negative (5/5) with broad-spectrum autofluorescence (5/5) and the appearance of lipofuscin with and without Wright staining. Most clinical diagnoses involved hepatic disorders (5/7 prospective and 3/4 retrospective cases) or pancreatitis (3/7 prospective and 2/4 retrospective cases), and some involved both; 8 of 11 dogs died within 7 days of admission.

Conclusions: Blue-green cytoplasmic inclusions uncommonly found in blood neutrophils ± monocytes of routine canine blood smears have stained and unstained properties of lipofuscin and suggest the presence of hepatocellular injury, often severe. Reporting these inclusions is recommended to guide clinical management.

Keywords: cytoplasmic granules; hematology; lipofuscin; liver failure; monocytes; neutrophils.