Allograft Acute Cellular Rejection in the Small Bowel

Epidemiology and Etiology:

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Common sites:

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Gross features:

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Histologic features:

· Mixed inflammatory infiltrate

· Primarily mononuclear

· Including blastic or activated lymphocytes

· Crypt injury

· Cytoplasmic basophilia

· Nuclear enlargement

· Hyperchromasia

· Decreased cell height

· Mucin depleition

· Loss of Paneth cells

· Inflammatory infiltration

· Increased numbers of crypt apoptotic bodies

· Distortion of villous and crypt architecture

· Wu et al. Grading Scheme:

· Indeterminate for ACR:

· Minimal localized inflammatory infiltrate

· Minimal crypt epithelail injury

· Increased crypt epithelial apoptosis (<6 apoptotic bodies / 10 crypts usually)

· None to minimal architectural distortion

· No mucosal ulceration

· Mild ACR:

· Mild localized inflammatory infiltrate

· Activated lymphocytes

· Tends to be concentrated around small venules in the lamina propria

· Mild crypt epithelial injury

· Increased crypt epithelial apoptosis (>6 apoptotic bodies / 10 crypts usually)

· Mild architectural distortion

· Villi variably shortened

· No mucosal ulceration

· Moderate ACR:

· Widely dispersed inflammatory infiltrate in lamina propria

· Diffuse crypt epithelial injury

· Increased crypt apoptosis with focal confluent apoptosis

· More prominent architectural distortion

· Possible mild to moderate intimal arteritis

· No mucosal ulceration

· Severe ACR:

· Features of moderate ACR plus mucosal ulceration

· Possible severe intimal arteritis or transmural arteritis may be seen

Immunophenotype:

Marker:

Sensitivity:

Specificity:

Molecular features:

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Other features:

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References:

· Wu T, Abu-Elmagd K, Bond G, et al. A schema for histologic grading of small intestine allograft acute rejection. Transplantation. 2003;75(8):1241-8.