Spontaneous Polycystic Kidneys with Chronic Renal Failure in an Aged House Musk Shrew (Suncus murinus)

Abstract

Polycystic kidney disease is one of the most common inheritable renal diseases, characterized by the formation of multiple fluid-filled renal cysts. This disease is a progressive and unfortunately incurable condition. A case of polycystic kidney with chronic renal failure in house musk shrew (Suncus murinus) is described. At clinical presentation, a 16-month-old Suncus murinus showed weight loss and coarse fur. Regarding the biochemical profile, total protein concentrations increased, resulting in a declined albumin: globulin ratio. Blood urea nitrogen and creatinine concentrations were markedly elevated, indicating the end stage of chronic renal failure. Serum amyloid A levels increased and revealed inflammatory reaction during the cyst formation. Histopathologically, multiple cysts were lined by a single layer of epithelial cells or low cuboidal epithelium. The contents were homogenous eosinophilic materials (mucopolysaccharides or mucoproteins) and these cysts contained abundant macrophages. There were also regeneration and dilatation of renal tubes and interstitial fibrosis. The atrophic glomeruli and glomerular capsules were thickened and hyalinized by dense amorphous mucopolysaccharides. These histopathological findings suggested that the pathogenesis of polycystic kidney disease shared a common mechanistic feature across species.

Keywords: dilatation; histopathology; house musk shrew (Suncus murinus); inflammation; interstitial fibrosis; macrophages; polycystic kidneys; renal tubes; serum amyloid A; serum biochemistry.

Figure 1

The outbred colony of Suncus murinus.

Figure 2

Microscopic finding of polycystic kidney. Note multiple cystic structures (open arrow) containing homogenous pinkish (asterisk) and/or eosinophilic (solid star) materials. Interstitial fibrosis (thin arrow) is also seen. HE stain. ×200, Bar = 100 μm.

Figure 3

Microscopic finding of polycystic kidney. The cyst contains a large number of macrophages (solid arrowhead). Vacuoles (open arrowhead) is observed around the low cuboidal epithelium. HE stain. ×400, Bar = 50 μm.

Figure 4

Microscopic finding of polycystic kidney. The cyst contains mucopolysaccharides or mucoproteins (solid star). The cysts are lined by a flattened single epithelium (open arrow). PAS stain. ×200, Bar = 100 μm.

Figure 5

Microscopic finding of polycystic kidney. Dense amorphous substances (open arrow) are deposited in the glomeruli and glomerular capsules. Thickening of basement membrane and hyalinization (thin arrow) are also seen. PAS stain. ×400, Bar = 50 μm.