Urinary System
Kidney, Interstitium - Infiltration, Cellular
Narrative
Comment:
Cellular infiltrates are routinely observed in the kidneys of rodents (Figure 1). The infiltrating cells are typically lymphoid or mononuclear cells, but other inflammatory cell types may comprise the infiltrates. These infiltrates generally increase with age. In many cases, they represent a background finding that has little pathologic significance. Cellular infiltration must be differentiated from inflammation. In general, cellular infiltration is diagnosed when the number of inflammatory cells is relatively low and no other indicators of inflammation (e.g., edema, hemorrhage, tissue damage) accompany the cells.
Recommendations:
Cellular infiltration should be diagnosed when it is treatment related. If it is not treatment related, its diagnosis is left to the discretion of the pathologist. If diagnosed, the cell type should be indicated in the diagnosis as a modifier (e.g., Kidney, Interstitium - Infiltration, Cellular, Lymphocyte).
References:
Seely JC. 1999. Kidney. In: Pathology of the Mouse: Reference and Atlas (Maronpot RR, Boorman GA, Gaul BW, eds). Cache River Press, Vienna, IL, 207-234.
Kidney, Interstitium - Infiltration, Cellular, Lymphocyte in a rat. There are relatively small numbers of lymphocytes in the renal cortical interstitium, with little to no tissue damage.
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Kidney, Interstitium - Infiltration, Cellular, Lymphocyte in a rat. There are relatively small numbers of lymphocytes in the renal cortical interstitium, with little to no tissue damage.