Lymphoproliferative Disease in the Rectum 4 Years After Local Mesenchymal Stromal Cell Therapy for Refractory Perianal Crohn's Fistulas: A Case Report.

Mesenchymal stromal cell [MSC] therapy is a new treatment for perianal fistulas in Crohn's disease. Although MSC therapy shows a favourable safety profile, long-term safety data are limited. We detected an Epstein Barr virus [EBV]-associated B cell lymphoproliferative lesion in the rectum of a patient 4 years after local administration of MSCs for his perianal fistulas. To investigate whether MSC therapy contributed to the development of this lymphoproliferative disease, we analyzed the possibility of EBV transfer via the MSC product and the persistence of MSCs in the lymphoproliferative lesion using short tandem repeat analysis.