JPC SYSTEMIC PATHOLOGY

URINARY SYSTEM

December 2023

U-M17 

 

SIGNALMENT (JPC #2182655): Tissue from a 35-day-old Finnish-Landrace cross lamb

 

HISTORY: Euthanized following a two-day episode of anorexia and depression

 

MICROSCOPIC DESCRIPTION: Kidney: Diffusely and globally, glomerular tufts are hypercellular and lobulated with increased mesangial cells and infiltration by variable numbers of neutrophils; glomerular capillary basement membranes are variably thickened by eosinophilic, homogenous material. Multifocally, glomeruli further exhibit one or more of the following changes: uriniferous spaces occasionally contain pale, eosinophilic, homogenous material (protein) and/or eosinophilic beaded fibrillar fibrin with cellular infiltration (crescent formation); and/or there is occasional hypertrophy and hyperplasia of the parietal and visceral layers of Bowman's capsule.  Multifocally, predominantly around glomeruli, the interstitium is expanded by small aggregates of many lymphocytes, fewer plasma cells, rare neutrophils, eosinophils, and variable amounts of fibrosis. Rarely, tubules are mildly ectatic and contain eosinophilic, homogenous material (proteinaceous fluid), hemorrhage, or sloughed cells and cellular and karyorrhectic debris (cellular casts). Multifocally, tubular epithelial cells exhibit one or more of the following changes: attenuation and flattening; microvacuolated epithelial cytoplasm with rare hyaline droplets (degeneration); slightly basophilic cytoplasm with vesiculate nuclei and occasional mitoses (regeneration). 

 

MORPHOLOGIC DIAGNOSIS: Kidney: Glomerulonephritis, membranoproliferative (mesangiocapillary), neutrophilic, diffuse, multifocal, mild, with crescent formation and lymphoplasmacytic interstitial nephritis, Finnish-Landrace cross, ovine. 

 

ETIOLOGIC DIAGNOSIS: Hereditary glomerulonephritis

 

GENERAL DISCUSSION:  

• Recessive inherited deficiency of C3 that is lethal in Finnish Landrace and Finnish Landrace cross lambs less than 4 months of age; very low levels of C3 
• Progressive disease that begins in utero with increasing subendothelial deposition of IgM, IgA, complement, and later IgG, leading to generalized immune complex disease

 

PATHOGENESIS:  

• Affected lambs absorb an as yet unknown colostral antigen > subendothelial deposition of immune complexes (IC) and complement in glomerular vessels > Type 1 membranoproliferative (mesangiocapillary) glomerulonephritis (MPGN)
• C3 deficiency may contribute to IC persistence through impaired solubilization of immune complexes, facilitating glomerular damage
• IC deposition stimulates endothelial cell swelling and proliferation and stimulates mesangial cell proliferation with release of IL-6 and TGF-beta
• IL-6 stimulates autocrine growth of mesangial cells
• TGF-beta stimulates production of the extracellular matrix
• Both mesangial and endothelial cell proliferation can lead to fibrosis

 

TYPICAL CLINICAL FINDINGS:  

• Many lambs are apparently normal at birth and later found dead of renal failure
• Clinical signs develop any time from within hours of birth to 3 months of age
• Dullness, ataxia, fine tremors, colic, convulsions, tachycardia, conjunctival edema, nystagmus, circling are all reported in affected lambs

 

TYPICAL GROSS FINDINGS:  

 

TYPICAL LIGHT MICROSCOPIC FINDINGS:  

• Finnish Landrace lambs
  • Mesangial proliferation, capillary wall thickening, crescent formation

• Severe vascular lesions of choroid plexuses and lateral ventricles in the brain due to IC deposition; leads to encephalopathy

• MPGN in general:  
  • Glomerular tufts are hypercellular (endocapillary and mesangial proliferation) with thickening of the glomerular basement membrane
  • Neutrophilic infiltration and margination within glomerular capillaries
  • +/- synechiae of Bowman’s capsule, glomerular basement membrane hyalinosis, afferent and efferent arteriolar hyalinosis, parietal cell proliferation, splitting of Bowman’s capsule, periglomerular fibrosis, deposition of fibrinogen and fibrinous thrombi in glomerular capillaries
  • In severe cases, proliferation of parietal epithelium, an influx of monocytes, and deposition of fibrin can occur within Bowman’s capsule, resulting in the formation of a semicircular, hypercellular, intraglomerular lesion known as a glomerular crescent

 

ULTRASTRUCTURE FINDINGS:  

• Subendothelial and mesangial electron-dense deposits of C3, IgM, IgA, and IgG
• Numerous neutrophils in the glomerular tuft
• Hypercellularity of mesangium

 

ADDITIONAL DIAGNOSTIC TESTS:

• Serum C3 is 5% of normal levels
• Serum biochemistry and urinalysis:  uremia, proteinuria, hypoalbuminemia, hyperphosphatemia, hypocalcemia

 

DIFFERENTIAL DIAGNOSIS:  

 

COMPARATIVE PATHOLOGY (Note: according to PBVD 7^th ed., “proliferative” is no longer recognized as a GN classification):  

• Dogs

• Leading cause of renal failure; commonly membranoproliferative
• Causes include: Canine adenovirus-1 (Infectious canine hepatitis); Borrelia burgdorferi (Lyme nephritis); pyometra; leishmaniasis; Dirofilaria immitis; neoplasms; autoimmune disease; and canine familial renal disease
• Inherited deficiency of C3 in Brittany spaniels leads to development of MPGN

• Cats

• Common in the cat; major cause of renal disease and nephrotic syndrome; predominantly membranous but MPGN also occurs; may be mistaken for primary segmental glomerulosclerosis so findings should be interpreted with caution in the absence of TEM and IF
• Causes include: FLV; FIP; feline progressive polyarthritis; autoimmune diseases; hematopoietic tumors

• Horse

• Common and rarely associated with renal failure; proliferative or membranoproliferative; anti-glomerular basement membrane disease documented in the horse (only domestic animal)
• Causes include:  Equine Infectious Anemia (lentivirus) (MPGN); Streptococcus equi (and purpura hemorrhagica); herpes virus infections
• ICs may appear atypical (fibrillar to crystalline) on TEM, similar to immunotactoid glomerulonephritis in humans

• Pigs

• Occurrence is sporadic and has little economic or clinical significance; lesions are membranoproliferative
• Causes include:  PDNS (PCV-2) (proliferative with crescent formation), Classical Swine Fever (pestivirus) and African swine fever
• Reported hereditary factor H deficiency caused lethal Type II MPGN (dense deposit disease) in Norwegian Yorkshire pigs

• Ruminants

• Evidence of glomerulonephritis is common but clinical disease is not
• Nephrotic syndrome in cattle is usually caused by amyloidosis
• Glomerular immune complexes most commonly derive from organisms involved in purulent metritis, from BVDV infection or infections with Trypanosoma congolense or Fasciola hepatica

• Mink: Aleutian mink disease 

• Chickens

• Occurs sporadically in clinically normal animals and in various poultry disease conditions; proliferative form is considered more common
• Causes include: inclusion body hepatitis (adenovirus), infectious bursal disease, infectious bronchitis, retroviruses, Mycoplasma synoviae, urolithasis, sodium chloride toxicity

• Mice:  Membranoproliferative glomerulonephritis with deposition of immune complexes within basement membranes has been reported in some strains of mice (especially NZB x NZW hybrids)

 

REFERENCES:  

1. Barthold SW, Griffey SM, Percy DH. Pathology of Laboratory Rodents and Rabbits. 4th ed. Ames, IA: Wiley Blackwell; 2016:102. Constable PD, Hinchcliff KW, Done SH, Gruenberg W. Diseases of the Kidney. In: Veterinary Medicine, A Textbook of the Diseases of Cattle, Horses, Sheep, Pigs, and Goats. 11th ed. New York, NY: Elsevier; 2017: 1110-1111.
2. Cianciolo RE, Mohr FC. Urinary system. In: Maxie MG, ed. Jubb, Kennedy, and Palmer’s Pathology of Domestic Animals. Vol. 2. 6th ed.  Philadelphia, PA: Elsevier; 2016:401-417.
3. Cianciolo RE, Mohr FC, Aresu L, et al. World Small Animal Veterinary Association renal pathology initiative: Classification of glomerular diseases in dogs. Vet Pathol. 2016;53(1):113-135.
4. Gonzales-Viera O, Ruoppolo V, Marigo J, et al. Renal lesions in cetaceans from Brazil. J Comp Pathol.  2015;152(4):345-354.
5. Matz-Rensing K, Lowenstine LJ. New World and Old World Monkeys. In: Terio KA, McAloose D, St. Leger J, eds. Pathology of Wildlife and Zoo Animals. London, UK: Academic Press; 2018:347.
6. McAloose D, Stalis IH. Prosimians. In: Terio KA, McAloose D, St. Leger J, eds. Pathology of Wildlife and Zoo Animals. London, UK: Academic Press; 2018:329-330.

1. Schmidt R, Reavill DR, Phalen DN. Pathology of Pet and Aviary Birds. 2nd ed. Ames, IA: John Wiley & Sons, Inc.; 2015:132.
2. Stockham SL, Scott MA. Fundamentals of Veterinary Clinical Pathology. 2nd ed. Hoboken, NJ: Wiley; 2013:385-386.

1. Sula, MM and Lane, LV. The urinary system. In: Zachary JF, McGavin MD, eds. Pathologic Basis of Veterinary Disease. 7^th ed. St. Louis, MO: Elsevier; 2022:729-731. 
2. Trang NT, Hirai T, Nabeta R, et al. Membranoproliferative glomerulonephritis in a calf with nephrotic syndrome.  J Comp Pathol.  2014;151(2-3):162-165.
3. Tizard IR. Veterinary Immunology: An Introduction. 8th ed. Philadelphia, PA: Elsevier; 2009:361-364.

 

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