Focal Ulcerative Ileocolitis, Cotton-Top Tamarin

The lesions are usually confined to the terminal part of the ileum and adjacent cecum; the intestinal wall may be thickened with a roughened peritoneal surface. The bowel lumen frequently contains fresh or digested blood (melena). The ileocolic lymph nodes are typically enlarged, 1.0 cm or more in diameter, soft, smooth and gray-white. Occasionally nodes may contain focal hemorrhages. Enlarged lymph nodes may coalesce and encase the ileocolic junction. This lymph-adenopathy may extend more diffusely to involve colonic and jejunal nodes. The mucosa near the ileocecal junction may be congested and thickened but ulcers are not usually visible to the naked eye.