Kidney, Papilla, Epithelium - Hyperplasia

Image of papilla epithelium hyperplasia in the kidney from a male F344/N rat in a chronic study
Kidney, Papilla, Epithelium - Hyperplasia in a male F344/N rat from a chronic study. The epithelium is thickened (arrows), and there are large clear spaces within the hyperplastic epithelium.
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Image of papilla epithelium hyperplasia in the kidney from a male F344/N rat in a chronic study
Kidney, Papilla, Epithelium - Hyperplasia in a male F344/N rat from a chronic study. A small focus of hyperplastic surface epithelial cells lines the renal papilla (arrows).
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comment:

Hyperplasia of the surface epithelium of the renal papilla can range from thickening of the epithelium ( Figure 1image opens in a pop-up window , arrows) to variably sized outgrowths of the epithelium with clear spaces amid the cells ( Figure 2image opens in a pop-up window ). Sometimes, these spaces contain eosinophilic material or cells. This lesion is commonly observed with advanced chronic progressive nephropathy (see Kidney - Nephropathy, Chronic Progressive).

recommendation:

Hyperplasia of the renal papillary epithelium should be diagnosed and given a severity grade whenever present.

references:

Frazier KS, Seely JC, Hard GC, Betton G, Burnett R, Nakatsuji S, Nishikawa A, Durchfeld-Meyer B, Bube A. 2012. Proliferative and non-proliferative lesions in the rat and mouse urinary system. Toxicol Pathol 40:14S-86S.
Abstract: http://www.ncbi.nlm.nih.gov/pubmed/22637735

McInnes EF. 2012. Wistar and Sprague-Dawley rats. In: Background Lesions in Laboratory Animals: A Color Atlas. Saunders Elsevier, Edinburg, 29.
Abstract: http://www.sciencedirect.com/science/book/9780702035197