Adenovirus infection within stromal cells in a pediatric small bowel allograft

Adenovirus infection is not uncommon in pediatric small bowel transplant recipients. Histopathologic findings include characteristic epithelial changes of intranuclear inclusions and smudging of nuclei. We present a case of adenovirus within stromal cells of the lamina propria in a biopsy from a small bowel allograft. Immunohistochemistry and double-labeled immunofluorescence were performed using antibodies against adenovirus, CD31, vimentin, cytokeratin, and CD163 on the allograft intestinal biopsy. Electron microscopy was done to confirm the presence of viral particles and to attempt to confirm the origin of the infected cells. The index biopsy showed scant cells within the lamina propria double-labeled with vimentin and adenovirus. Several cells showed predominantly cytoplasmic staining for adenoviral antigen. Intranuclear adenoviral particles were found in several cells of the lamina propria by electron microscopy. A subsequent biopsy showed typical adenoviral intranuclear inclusions within surface enterocytes. Adenovirus may infect stromal cells within the lamina propria. Although the typical location of adenoviral inclusions in small bowel is the surface epithelial cell nuclei, some cases may show inclusions within stromal cells. This observation may be important in the pathobiology of adenoviral infection, especially in the setting of pediatric transplantation. This finding should alert pathologists examining small bowel transplant biopsies, particularly those biopsies with extensive ulceration, to include careful surveillance of the lamina propria.