Histopathologically, multifocal coagulation necroses characterized by
acellular homogenous eosinophilic appearance and mononuclear cell
infiltrations surrounded necrotic cell debris. In severe cases,
widespread hemorrhages showed association with hepatic necroses.
Hepatocytes mostly showed parenchymatous degeneration, cytoplasmic
swelling and they had clear, hyperchromatic nuclei. In some nuclei of
the hepatocytes, intranuclear basophilic viral inclusions were observed
(Figure 2). In kidneys, multifocally localized interstitial lymphocytes
and plasma cell infiltrations in the cortex, tubular hydropic
degenerations were detected. In two cases, interstitial pnemonia,
alveolar epithelia hyperplasia, and bronch/iolitis were seen. In
proventriculus mucosae, numerous heterophilic leucocyte infiltrations
were present in the submucosae. FAdV-4 antigen specific immunoreactions
were observed in degenerated hepatocytes and in the necrotic areas,
kidney tubul epithelia, interstitital inflammatory cells and in
urethelial epithelia, alveolar and bronchial epithelia in the lungs.
FIGURE 2. a) Severe coagulation necrosis, homogeneous
eosinophilic appearance and some structural remnants of hepatic cords
were visible but the hepatocytes were completely necrotic (arrows). At
the periphery, focal lymphocyte and macrophage accumulations (arrow
heads) were seen in the liver, H&E, Bar= 300 μm.
b) Clear nucleus due to characteristic circular margination of the
chromatin in the hepatocytes. Some degenerated hepatocytes had
basophilic intranuclear viral inclusions (arrow heads and inset). Liver,
Hematoxylin-eosin, Bar= 45 μm.
c) Hydropic degeneration and necrosis of the cortical tubule epithelia,
and in healthy tubular epithelia nuclei seemed clearbut contained
numerous intranuclear basophilic inclusions. Hematoxylin-eosin, Bar= 90
μm.
d) FAdV-4 antigen immunopositive reactions, red dots, in the necrotic
areas and degenerated hepatocytes (arrowheads). Avidin biotin complex
immunoperoxidase test, FAdV-4 antibody, Gill’s hematoxylin
counterstaining, Bar= 180 μm.
e) Immunoperoxidase positive reactions in the degenerative and necrotic
tubule epithelia of the kidney. Avidin biotin complex immunoperoxidase
test, FAdV-4 antibody, Gill’s hematoxylin counterstaining, Bar= 180 μm.
f) Strong viral antigen immunopositivity on the bronchiolar epithelia
(arrowheads= and alveolar walls. Avidin biotin complex immunoperoxidase
test, FAdV-4 antibody, Gill’s hematoxylin counterstaining, Bar= 300 μm.