PTLD involvement of large bowel. Two adjacent but noncontiguous
ulceronodular lesions are seen on the
luminal aspect of this large bowel specimen. The borders have a slightly
heaped-up appearance, but the process subsides almost immediately beyond the
confines of the ulcerated masses. The green discoloration corresponds to loss of
mucosal lining cells with overlying fibrinoinflammatory debris, often with large
numbers of bacteria.