Urinary System

Kidney, Renal Tubule - Degeneration

Narrative

Comment:

Degeneration is a nonspecific entity that can arise from any number of etiologies that perturb cell function and is often an early indicator of necrosis. Degeneration, in some cases, is preceded by vacuolation (Figure 1). In general, degeneration is characterized by several morphologic and variable cell features, such as cell swelling with or without cytoplasmic vacuolation and pale-staining and fragmented cytoplasm (Figure 2). Degeneration must be distinguished from apoptosis, which represents the normal process of cell turnover in the kidney. Necrosis generally includes cell swelling, nuclear pyknosis and/or karyorrhexis, and cellular sloughing. Degeneration may be either reversible or irreversible.

Recommendations:

Degeneration should be diagnosed and graded. If applicable, the location of the affected tubule(s) should be included as a site modifier in the diagnosis. Associated lesions, such as inflammation or regeneration, should not be diagnosed separately unless warranted by severity but should be described in the pathology narrative.

Related Links:

Kidney - Renal Tubule - Cytoplasmic Alteration
Kidney - Renal Tubule - Necrosis
Kidney - Renal Tubule - Regeneration
 

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

All Images

Kidney, Renal tubule - Degeneration in a male Tg.Ac (FVB/N) hemizygous mouse from a subchronic study. The degeneration of cortical tubule epithelial cells is characterized by vacuolation of the cytoplasm and pyknosis of the nuclei.

Kidney, Renal tubule - Degeneration in a female F344/N rat from a subchronic study. In this case, the degeneration is characterized by tubule cells with an eosinophilic tinctorial change and cytoplasmic vacuolation.

Authors and Reviewers

Authors 

John Curtis Seely, DVM, DACVP
Senior Pathologist
Experimental Pathology Laboratories, Inc.
Research Triangle Park, NC

Amy Brix, DVM, PhD, DACVP
Senior Pathologist
Experimental Pathology Laboratories, Inc.
Research Triangle Park, NC

Reviewers

Kendall S. Frazier, DVM, PhD, DACVP, DABT
Director, Cellular and Molecular Pathology, Safety Assessment
GlaxoSmithKline
King of Prussia, PA

Gordon C. Hard, BSc, BVSc, PhD, DSc, FRCPath, FRCVS, FAToxSci, DACVP
Expert Consultant
Tairua, New Zealand

Susan A. Elmore, MS, DVM, DACVP, DABT, FIATP
Staff Scientist, NTP Pathologist
NTP Pathology Group
National Toxicology Program
National Institute of Environmental Health Sciences
Research Triangle Park, NC