December 2017

Signalment (JPC #1565530):  Rat

HISTORY:  Tissue from an old laboratory rat

HISTOPATHOLOGIC DESCRIPTION:  Kidney:  Diffusely, all levels of the nephron are moderately to severely affected by the following changes.  There is a mild reduction in the number of glomeruli and multifocally those remaining have one or more of the following changes:  The basement membrane of Bowman’s capsule is variably thickened and hyalinized  and there is periglomerular fibrosis; the parietal epithelium of Bowman’s capsule is hypertrophied; there are multifocal adhesions of the glomerular tuft to Bowman’s capsule (synechia); the uriniferous space is dilated; there is segmental or global glomerulosclerosiswith multifocal obsolescence of glomerular tufts.  Diffusely within the cortex and medulla, tubules have one or more of the following changes:  swollen epithelium with indistinct cell borders and microvacuolated eosinophilic cytoplasm (degeneration); marked tubular ectasia with attenuation and/or loss of epithelium; abundant basophilic cytoplasm with vesiculate nuclei (regeneration) that occasionally piles up and forms irregular tubules (hyperplasia), with multifocally thickened basement membranes; or shrunken atrophic tubules with attenuated epithelium.  Ectatic tubule lumina often contain one or more of the following:  variable amounts of pale granular to brightly eosinophilic homogenous proteinaceousmaterial (proteinosis, hyaline casts), deeply basophilic granular material (mineralization), sloughed epithelial cells with cellular and karyorrhectic debris (necrosis), few degenerate neutrophils, and rare erythrocytes.  Tubular epithelia, primarily of the proximal convoluted tubule, multifocally contain variably distinct, irregularly round, intracytoplasmic 1-4um diameter eosinophilic hyaline droplets.  Diffusely, the interstitium is moderately expanded by fibrosis, edema, and multifocal infiltrates of low numbers lymphocytes and plasma cells.  Multifocally there is a small amount of light golden-brown material (hemosiderin) within the interstitium and tubules.  Multifocally, the capsular surface is irregular and undulant. 

MORPHOLOGIC DIAGNOSIS:  Kidney:  Glomerulosclerosis, segmental to global, multifocal, marked, with synechia, periglomerular fibrosis, tubular degeneration, necrosis, and regeneration, marked tubular ectasia with proteinosis, and chronic interstitial nephritis, rat, rodent.

CONDITION:  Chronic progressive nephropathy (CPN)

SYNONYMS:  Glomerulosclerosis, progressive glomerulonephrosis, “old rat nephropathy”, protein overload nephropathy, chronic renal disease, chronic nephritis, dietary nephritis, glomerulonephritis, chronic progressive glomerulonephropathy, glomerular hyalinosis, progressive renal disease, spontaneous nephrosis, others











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