JPC SYSTEMIC PATHOLOGY

URINARY SYSTEM

December 2023

U-M22 (NP)

 

Signalment (JPC 1629346): Dog

 

HISTORY: Slide U-M22a: Incidental histologic finding in a dog

 

HISTOPATHOLOGIC DESCRIPTION: Kidney: Multifocally within the cortex, proximal tubular epithelial cells contain single brightly eosinophilic, acicular, 5 by 10-15 µm intranuclear inclusions which are occasionally elongate and distend the nucleus. Focally, there is distortion of the architecture of a glomerular tuft by a closely packed aggregate of polygonal foam cells with vacuolated, pale eosinophilic cytoplasm (glomerular lipidosis). Multifocally, proximal tubular epithelial cells and less often glomerular podocytes contain brown to yellow globular intracytoplasmic pigment.  

 

Liver: Occasional hepatocytes contain intranuclear inclusions as previously described.

 

MORPHOLOGIC DIAGNOSIS: 1. Kidney, proximal tubule epithelium:  Intranuclear inclusions, multiple, with minimal glomerular lipidosis, breed not specified, canine

 

2. Liver, hepatocytes:  Intranuclear inclusions, few. 

 

Signalment (JPC Accession #850256-4A): Rhesus monkey

 

HISTORY: Slide U-M22b: Incidental histologic finding in a rhesus monkey

 

HISTOPATHOLOGIC DESCRIPTION: Kidney: Multifocally, pelvic urothelial cells contain 1 to 2 round to oval, up to 10 µm diameter, brightly eosinophilic, granular, intracytoplasmic inclusion bodies.

 

MORPHOLOGIC DIAGNOSIS: Kidney, pelvic urothelium: Intracytoplasmic inclusions, few, rhesus macaque, nonhuman primate.

 

ETIOLOGIC DIAGNOSIS: Nonspecific renal and hepatic inclusions.

 

CAUSE: Unknown

 

GENERAL DISCUSSION: 

• Nonspecific intranuclear inclusions are a common finding in the kidneys and liver of older dogs (ACIN inclusions); although these inclusions are crystalline, they are non-birefringent 

• In the kidneys, they are often located in the proximal tubules and are eosinophilic, crystalline and referred to as “brick inclusions”

• Inclusions may also be found in the urinary bladder of the dog and monkey
• Not considered pathologically significant

 

PATHOGENESIS: Unknown 

 

TYPICAL CLINICAL FINDINGS: None

 

TYPICAL GROSS FINDINGS: None

 

TYPICAL LIGHT MICROSCOPIC FINDINGS:

 

ULTRASTRUCTURAL FINDINGS:

• Varies with the type of inclusion but are apparently composed of protein

 

ADDITIONAL DIAGNOSTIC TESTS:

• EM, toxicology, or PCR to rule out infectious or toxic causes  
• Inclusions are acid-fast

 

DIFFERENTIAL DIAGNOSIS:

• Viral infections with intranuclear inclusions (herpesvirus, parvovirus, morbillivirus, polyomavirus, adenovirus, iridovirus) 
• Lead toxicity: Intranuclear inclusions may be present in renal tubular epithelium; inclusions are acid-fast and noncrystalline
• Cytoplasmic invagination into the nucleus can be mistaken for viral inclusions; may be evident in hepatocytes in a chronically injured liver

 

COMPARATIVE PATHOLOGY:

• Mice: 

• Renal tubular intranuclear inclusions have been reported in immunocompromised NSG mice infected with mouse kidney parvovirus (MKPV), also known as murine chapparvovirus (MuCPV); in comparison, renal tubular intranuclear inclusions are rarely reported in MKPV-infected immunocompetent CD-1 and Swiss Webster mice (Edmondson, Vet Pathol 2020)
• Eosinophilic neuronal intracytoplasmic inclusions have been reported in the thalamus of aging mice and in the renal tubular epithelium of ICR mice

• Goats may have large eosinophilic intranuclear inclusions in hepatocytes and renal collecting duct epithelium; the pathogenesis is unclear but it is referred to as “nuclear glyogenosis”

 

REFERENCES:

1. Cianciolo RE, Mohr FC. Urinary system. In: Maxie MG, ed. Jubb, Kennedy, and Palmer’s Pathology of Domestic Animals. 6th ed. St. Louis, MO: Elsevier; 2016:430.
2. Cullen JM, Stalker MJ. Liver and biliary system. In: Maxie MG, ed. Jubb, Kennedy, and Palmer's Pathology of Domestic Animals. 6th ed. Vol 2. Philadelphia, PA: Elsevier Saunders;2016:270.
3. Edmondson EF, Hsieh WT, Kramer JA, et. al. Naturally Acquired Mouse Kidney Parvovirus Infection Produces a Persistent Interstitial Nephritis in Immunocompetent Laboratory Mice. Vet Pathol. 2020 Nov;57(6):915-925.

Click the slide to view.

---