Polycystic kidney in a pig
In a 6 months old hybrid pig a bilateral alteration was seen of the kidneys. These showed a loss of structure, with an obvious atrophy of the renal medulla and also, to a lesser extent, of the renal cortex parenchyma which presented with a microcystic appearance. The urethers were significantly dilated and thickened.
Histologically the renal parenchyma was almost entirely occupied by cysts lined by a simple epithelium, some of which contained glomerular structures more or less atrophied. In the interstitium fibrosis and a mild mononuclear inflammatory component could be appreciated. Scattered remnants of apparently normal (probably functional) renal parenchyma were also observed .
The lesions observed point to a disturbance of normal renal development causing microcystic structures in virtually all of the renal cortex and a significant loss of renal medulla. Although this can't be classified into known types of renal lesionin the differential diagnosis we may include:
- Congenital polycystic kidney. Mutations in the PKD gene(polycystic kidney disease) can result in this type of lesion which is often hereditary.
- Acquired Polycystic Kidney , perhaps as a result of a chronified interstitial inflammation or due to other causes that can trigger the onset of cysts (hypokalemia, some medications, etc).
- Renal dysplasia (defect in the formation of nephrons), also congenital. But the focal presence of correctly formed nephrons makes this option less likely.