The Cooperative Clinical Trial in Transplantation (CCTT) developed criteria for the histologic diagnosis of acute renal allograft rejection.


Histologic findings:

(1) percent of cortex showing an interstitial mononuclear infiltrate

(2) interstitial edema

(3) tubular degeneration or injury (epithelial cells that are thinned, detached, vacuolated, necrotic, mitotically active, with cytoplasmic basophilia or with nuclear enlargement)

(4) activated lymphocytes (enlarged with basophilic cytoplasm, a large vesicular nucleus and 1 or more nucleoli)

(5) tubulitis (tubular inflammation with >= 1 mononuclear cells penetrating the tubules either (a) between tubular epithelial cells or (b) between a tubular epithelial cell and its basement membrane)

(6) endotheliatis or endarteritis (mononuclear cell endothelial inflammation, with at least 1 inflammatory cell under the endothelium)

(7) arterial or arteriolar fibrinoid necrosis

(8) arterial or arteriolar transmural inflammation

(9) vascular thrombosis

(10) parenchymal necrosis and/or infarction

(11) parenchymal hemorrhage

Histologic Findings:

Histologic Pattern

(1) >= 5% of cortex show interstitial mononuclear cell infiltrate, AND

(2) at least 2 of the following: edema, tubular degeneration, or activated lymphocytes, AND

(3) tubulitis involving >= 3 tubules in 10 serial high dry power fields (40x) in area with the maximal infiltrate

Type I

endotheliatis and/or endarteritis

Type II

arterial or arteriolar fibrinoid necrosis or transmural inflammation; may show vascular thrombosis, parenchymal necrosis and/or hemorrhage

Type III



• There is no provision made for chronic allograft rejection.


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