JPC SYSTEMIC PATHOLOGY
URINARY
December 2023
U-M12 (NP)
Signalment (JPC #82-2228): Angora goat
HISTORY: On gross examination, the kidneys appeared uniformly brown, and the discoloration was limited to the cortices of both kidneys.
HISTOPATHOLOGIC DESCRIPTION: Kidney: Approximately 40% of the proximal convoluted tubules within the renal cortex have reddish brown to black pigmented basement membranes that are thickened up to 8-12 µm wide. Rarely, tubules contain granular basophilic material (mineral).
MORPHOLOGIC DIAGNOSIS: Kidney, cortex, proximal convoluted tubule basement membranes: Pigmentation, multifocal, moderate, Angora, caprine.
CONDITION: Cloisonné kidney
CAUSE: Unknown
GENERAL DISCUSSION:
- Nonclinical pigmentary condition in goats
- Does not interfere with renal function
- Name derived from the resemblance of the microscopic pattern to the cloisonné technique of inlay of metal wire in porcelain
PATHOGENESIS:
- Unknown
- A hemolytic pathogenesis has been suggested
- Low levels of erythrocytic glucose-6-phosphate dehydrogenase and glutathione, plus elevated serum-iron binding saturation, predispose erythrocytes to fragility
- Ferritin and hemosiderin are deposited, presumed to be the result of repeated episodes of intravascular hemolysis
- Basement membrane thickening is postulated to be due to ferritin and hemosiderin deposition; however the chemical nature of the material has not been established and usually it does not stain for iron
TYPICAL GROSS FINDINGS:
- Uniform brown-black discoloration throughout the renal cortex, stopping abruptly at the corticomedullary junction
TYPICAL LIGHT MICROSCOPIC FINDINGS:
- Curving, wire-like dark brown to gray/brown pigmented thickening of the basement membranes of proximal convoluted tubules
DIFFERENTIAL DIAGNOSIS:
- Gross: Renal hemosiderosis, post-mortem discoloration, hemoglobinuric nephrosis (gunmetal blue kidney)
- The gross appearance, with the discoloration affecting only the cortex and stopping abruptly at the cortico-medullary junction differentiates from all other entities
COMPARATIVE PATHOLOGY:
- Described only in the goat
References:
1. Cianciolo RE, Mohr FC. Urinary system. In: Maxie MG, ed. Jubb, Kennedy, and Palmer’s Pathology of Domestic Animals. Vol 2. 7th ed. St. Louis, MO: Elsevier; 2016: 429.
2. Sula MM, Lane LV. The urinary system. In: McGavin MD, Zachary JF, ed. Pathologic Basis of Veterinary Disease. 6th ed. St. Louis, MO: Elsevier; 2022: 714.
