Early Changes of Gut GVHD: Differential Diagnosis and Criteria for Crypt Cell Apoptosis

The early changes of GVHD overlap with those caused by mucosal damage from conditioning chemoradiation therapy. This overlap occurs in the first several weeks post-transplant. The widespread distribution of the mucosal damage including marked edema, hemorrhage, architectural disarray, and crypt atypia suggests chemoirradiation damage. In contrast, the earliest change of GVHD is individual crypt cell apoptosis. The overlap of conditioning toxicity with GVHD is much less likely in patients who receive nonmyeloablative or reduced intensity conditioning. The precise definitions for apoptotic enterocytes, crypt destruction, and crypt abscesses have now been standardized, allowing reliable inter-institutional comparisons. These are important to allow comparison of results from different institutions. A number of other entities cause apoptotic changes resembling GVHD, including infections and some drugs such as NSAIDs, proton pump inhibitors, and mycophenolate mofetil.