PATHOLOGY OF INTESTINAL TRANSPLANTATION IN CHILDREN

The role of mucosal biopsy in the monitoring of pediatric intestinal a llografts is analyzed. We performed a retrospective review of all biop sy, resection, and autopsy material from 22 bowel allografts in 21 pat ients, followed from 6 months to 3 1/4 years and treated on an immuno- suppressive regimen based on FK 506 (Tacrolimus). There were 579 biops ies, of which 35 were stomal, with two to three fragments taken at eac h biopsy. There were three explanted bowels and three autopsies. Stoma l biopsies proved to be inappropriate for monitoring. Biopsies with th ree to five pieces of tissue per site, under endoscopic direction, pro vided the most information. Early cellular infiltrate with lymphoid ac tivation in the absence of epithelial apoptotic figures was not consid ered sufficient to diagnose rejection although preceded it in most ins tances. At least two apoptotic figures in a gland or several single ap optotic cells in the presence of a lymphoid infiltrate with activated lymphoid follicles and prominent endothelium correlate best with clini cal rejection and response to antirejection measures. Epstein-Barr vir al disease is common in this population, and early, late, and nonconti guous bowel involvement can be subtle and difficult to distinguish fro m rejection, though without the apoptosis. Epstein-Barr virus in situ probes are essential to make the differential diagnosis and the two co nditions may co-exist. Mucosal biopsy monitoring appears to be of clin ical utility and is part of a program that involves clinical, endoscop ic, microbiological, and morphologic assessment.