Kidney, Renal Tubule - Cast

Image of renal tubule cast in the kidney from a male F344/N rat in a chronic study
Kidney, Renal tubule - Cast in a male F344/N rat from a chronic study. Linear, hyaline (protein) casts are present in the medullary tubules.
Figure 1 of 3
Image of renal tubule cast in the kidney from a male F344/N rat in a subchronic study
Kidney, Renal tubule - Cast in a male F344/N rat from a subchronic study. Granular casts are present in the outer medulla.
Figure 2 of 3
Image of renal tubule cast in the kidney from a male F344/N rat in a subchronic study
Kidney, Renal tubule - Cast in a male F344/N rat from a subchronic study. Higher magnification of a granular cast containing necrotic cellular debris.
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comment:

Intratubular casts may have various compositions with different morphologic and staining characteristics. Both hyaline and granular casts may be observed in a number of renal diseases. Commonly observed casts are hyaline (eosinophilic, homogeneous proteinaceous) casts associated with increased glomerular permeability such as with chronic progressive nephropathy ( Figure 1image opens in a pop-up window ) and granular (necrotic cellular debris) casts indicative of previous tubule cell necrosis associated with chemicals that induce α2u-globulin nephropathy ( Figure 2image opens in a pop-up window and Figure 3image opens in a pop-up window ).

recommendation:

Tubule casts should be diagnosed according to their morphologic appearance (granular, hyaline, etc.) and given a severity grade. Hyaline casts observed as a component of chronic progressive nephropathy should not be diagnosed separately. Details of the casts, such as location within the kidney (e.g., the junction of the inner and outer stripes of the outer medulla, the typical location of casts associated with α2u-globulin nephropathy) should be discussed in the pathology narrative.

references:

Alden CL. 1986. A review of unique male rat hydrocarbon nephropathy. Toxicol Pathol 14:109-111.
Abstract: http://www.ncbi.nlm.nih.gov/pubmed/2424069

Hard GC, Alden CL, Bruner RH, Frith CH, Lewis RM, Owen RA, Krieg K, Durchfeld-Meyer B. 1999. Non-proliferative lesions of the kidney and lower urinary tract in rats. In: Guides for Toxicologic Pathology. STP/ARP/AFIP, Washington, DC, 1-32.

Peter CP, Burek JD, Van Zwieten MJ. 1986. Spontaneous nephropathies in rats. Toxicol Pathol 14:91-100.
Abstract: http://www.ncbi.nlm.nih.gov/pubmed/3715332