JPC SYSTEMIC PATHOLOGY
URINARY SYSTEM
January 2018
U-N05 (NP)

SIGNALMENT (JPC #2018633): 12-year-old male German Shepherd Dog

HISTORY:  Incidental finding at necropsy

HISTOPATHOLOGIC DESCRIPTION:  Kidney (2 sections):  Focally expanding the corticomedullary junction, widely separating and often replacing tubules and glomeruli, and compressing adjacent parenchyma, is a round, 5 mm diameter, unencapsulated, well-demarcated, sparsely-cellular neoplasm composed of interlacing streams and bundles of spindle to stellate shaped cells separated by abundant dense collagenous matrix.  Neoplastic cells have indistinct cell borders, scant eosinophilic fibrillar cytoplasm, and an oval to elongate nucleus with finely-stippled chromatin and a small nucleolus.  No mitoses are observed.  Frequently surrounding the neoplasm, and multifocally expanding the interstitium of the remaining kidney, there are small aggregates of plasma cells and lymphocytes, and variable amounts of fibrosis.  Multifocally, remaining glomeruli exhibit one or more of the following changes:  thickened Bowman’s capsule with hypertrophy and hyperplasia of the visceral epithelial lining and occasional attachment to the glomerular tuft (synechiae); ectatic uriniferous space containing proteinaceous fluid; rare glomerular sclerosis and obsolescence; and periglomerular fibrosis.  Multifocally, tubules are ectatic and contain proteinaceous fluid, and tubular epithelial cells are occasionally hypertrophied with vacuolated cytoplasm (degenerate).  Focally there is a depression in the renal capsule, which is subtended by a wedge-shaped subcapsular area composed of moderate amounts of fibrous connective tissue that separates, surrounds, and replaces glomeruli and tubules (infarct).  Remaining glomeruli in the infarcted area are variably sclerotic to obsolescent.

MORPHOLOGIC DIAGNOSIS: 

  1. Kidney, corticomedullary junction: Renal interstitial cell tumor (fibroma), German Shepherd Dog, canine.
  2. Kidney: Nephritis, interstitial, lymphoplasmacytic, multifocal, mild, with multifocal glomerulosclerosis and obsolescence.
  3. Kidney, cortex: Infarct, chronic, focal.

CONDITION:  Renal interstitial cell tumor

GENERAL DISCUSSION: 

TYPICAL GROSS FINDINGS: 

TYPICAL LlGHT MICROSCOPIC FINDINGS: 

ULTRASTRUCTURAL FINDINGS:

ADDITIONAL DIAGNOSTIC TESTS: 

DIFFERENTIAL DIAGNOSIS:

COMPARATIVE PATHOLOGY: 

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; 2016:447.
  2. Diters RW, Wells M: Renal interstitial cell tumors in the dog. Vet Pathol. 1986;23:74-76.
  3. Meuten DJ, Meuten TLK: Tumors of the urinary system. In: Meuten DJ. Ed. Tumors in Domestic Animals. 5th ed. Ames, IA: Iowa State Press; 2017:650-651.
  4. Picut CA, Valentine BA: Renal fibroma in four dogs. Vet Pathol. 1985:22:422-423.


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