JPC SYSTEMIC PATHOLOGY

URINARY SYSTEM

January 2024

U-T04 (NP)

 

Signalment (JPC #1713077): Multiple male mice.

 

HISTORY: An accident in the hallway of a laboratory animal facility resulted in the leakage of several bottles of chloroform. The following day many male mice housed in the facility were found dead.

 

HISTOPATHOLOGIC DESCRIPTION: Kidney: Multifocal proximal tubular epithelial cells are swollen with pale granular cytoplasm (degeneration) or are shrunken with hypereosinophilic cytoplasm and a pyknotic nucleus (necrosis). The tubular epithelial cells in these areas are either attenuated or swollen with numerous intracytoplasmic, variably sized (up to 15 µm diameter) eosinophilic hyaline globules. Multifocally within the cortex, Bowman’s space and moderate numbers of renal tubules are mildly dilated and contain bright eosinophilic homogenous fluid (proteinosis) or granular eosinophilic cellular debris. Less affected cortical and medullary tubules are dilated and contain proteinaceous fluid. There is a focal aggregation of lymphocytes within the deep medulla adjacent to the renal pelvis.

 

MORPHOLOGIC DIAGNOSIS: Kidney, proximal tubules: Degeneration and necrosis, acute, multifocal, moderate, with proteinosis, mouse, rodent.

 

ETIOLOGIC DIAGNOSIS: Chloroform nephrosis

 

CAUSE: Chloroform (CHCI₃)

 

GENERAL DISCUSSION:  

• Prototypical organohalide (halogenated hydrocarbon); organic solvent used in sanitizing avian production facilities, degreasing, dry cleaning and paint removers
• Chloroform toxicity results in acute coagulative renal tubular necrosis (especially proximal tubules) in male mice and hepatotoxicity in males and females
• Male DBA and C3H mice are especially sensitive due to the presence of cytochrome P450 isoenzyme 2E1; F344 rats are also sensitive but less so than these mouse strains
• Castration eliminates the nephrotoxic effects in male mice due to decrease of renal cytochrome P450 and incites nephrotoxic effects in female mice treated with testosterone

 

PATHOGENESIS:  

• Inhalation or ingestion of chloroform 
• Increased binding of chloroform in males (6 x that of females) because the action of chloroform is mediated via the androgen receptor
• Metabolism of chloroform (CHCI₃) to unstable trichloromethanol to phosgene (COCI2) occurs in the proximal renal tubule epithelium by cytochrome P-450 (mixed function oxidase) system
• Phosgene depletes renal glutathione resulting in autocatalytic peroxidative degradation of membranes > glutathione conjugation with chloroform metabolites reduces or prevents covalent binding with tissue macromolecules
• Covalent adduct formation with DNA may cause renal and hepatic carcinomas in rats

 

TYPICAL CLINICAL FINDINGS:  

• Lethargy, tremors and convulsions
• Death 1-10 days later
• Deaths may be primarily in male animals
• Clinical Pathology: Proteinuria, glucosuria, elevated BUN, ALP, ALT, AST, CK            

 

TYPICAL GROSS FINDINGS:  

• The kidneys are pale and swollen with a finely granular surface  
• White capsular mottling and cortical streaks due to calcification of necrotic tubules (nephrocalcinosis) may occur in survivors

         

TYPICAL LIGHT MICROSCOPIC FINDINGS:  

• Coagulative necrosis of primarily proximal renal tubular epithelial cells
• Tubules may contain hyaline casts and protein
• The glomeruli, collecting tubules and renal papilla are not affected
• Hepatic lesions are characterized by centrilobular necrosis, acute cell swelling (hydropic degeneration) and/or fatty degeneration of hepatocytes and nodular hyperplasia
• Myocardial and neuronal degeneration and lymphocytic necrosis 

 

ULTRASTRUCTURAL FINDINGS:  

•   Swelling of tubular epithelial cells                     

•   Swollen mitochondria  

•   Dilated and fragmented endoplasmic reticulum   

•   Loss of villi

•   Focal rarefaction of cytoplasmic matrix

 

DIFFERENTIAL DIAGNOSIS:

• Renal tubule damage is nonspecific; mercury bichloride, uranyl nitrate, and potassium dichromate produce similar lesions
• Chloroform and 1,1,2-trichloroethane are the only chlorinated compounds that produce severe renal disease 

 

COMPARATIVE PATHOLOGY:  

• Other halogenated hydrocarbons metabolized by cytochrome P450 to hepatotoxic/nephrotoxic metabolites: carbon tetrachloride, bromobenzene, hexachloroethane, tetrachloroethylene
• Susceptibility to chloroform nephrotoxicity is a species- and sex-specific response of the male mouse
• F-344 male rats are susceptible but require a higher concentration
• Mice and rats are used as animal models for acute and chronic chloroform nephrotoxicity and hepatotoxicity
• Induces hepatocellular carcinomas in B6C3F1 mice and renal epithelial tumors in Osborne-Mendel rats in long-term studies
• Humans: Acute exposure to high levels à dizziness and confusion, CNS depression, and coma; lower levels associated with liver and kidney toxicity

 

REFERENCES:  

1. Barthold SW, Percy DH. Pathology of Laboratory Rodents and Rabbits. 4^th ed. Ames, Iowa: Iowa State University Press; 2016:103.
2. Cullen JM, Stalker MJ. Liver and Biliary System. In: Maxie MG, ed. Jubb, Kennedy & Palmer's Pathology of Domestic Animals. Vol 2. 6th ed. St. Louis, MO: Elsevier; 2016:332. 
3. Gathumbi PK, Mwangi JW, Mugera GM, Njiro SM. Toxicity of chloroform extract of Prunus Africana stem bark in rats: gross and histologic lesions, Phytother Res. 2002; 16(3):244-7.
4. Haschek WM, Rousseaux CG, Wallig MA. Kidney and lower urinary tract. Fundamentals of Toxicological Pathology. 2^nd ed. San Diego, CA: Academic Press; 2010:287.
5. Kumar V, Abbas AK, Aster JC. Environmental and nutritional diseases. In: Kumar V, Abbas AK, Aster JC, eds. Robbins & Cotran Pathologic Basis of Disease. 10th ed. Philadelphia, PA: Elsevier Saunders; 2021:414.
6. Miller MA, Lyle LT, Zachary JF. Mechanisms and Morphology of Cellular Injury, Adaptation, and Death. In: Zachary JF, ed. Pathologic Basis of Veterinary Disease. 7th ed. St. Louis, MO: Elsevier; 2022:26, 33.
7. Schnellmann RG. Toxic responses of the kidney. In: Klaassen CD, ed. Casarett and Doull’s Toxicology, The Basic Science of Poisons. 6th ed. San Francisco, CA; McGraw-Hill; 2001:508.
8. Sebastian MM, Baskin SI, Czerwinski SE. Renal toxicity. In: Gupta RC, ed. Veterinary Toxicology. 1^st ed. San Diego, CA: Elsevier; 2007:162-163.
9. Sehata S, et al. 26 week carcinogenicity study of chloroform in CB6F1 rasH2-transgenic mice. Toxicol Pathol. 2002 May-Jun;30(3):328-38.

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