Lung transplantation complicated by graft-versus-host disease and confounded by incidental transfusion-associated macrochimerism

BACKGROUND: Passenger lymphocyte–mediated graft‐versus‐host disease (GVHD) in solid organ transplantation (SOT‐GVHD) is considered a rare complication, particularly among recipients of lung allografts. The risk of transfusion‐associated GVHD (TA‐GVHD) in solid organ transplants is also considered rare. The suspicion of either may be heralded by signs and symptoms of GVHD in the company of a population of passenger lymphocytes in excess of 1 percent (microchimerism). This case report illustrates the challenge of a patient who presented with macrochimerism both from the lung transplant allograft and from transfusions. STUDY DESIGN AND METHODS: Chimerism assessments of the pre‐ and posttransplant donor lung, and the recipient's aplastic marrow, were made using DNA‐based polymerase chain reaction testing. RESULTS: Macrochimerism was observed in both the posttransplant aplastic host marrow and the engrafted donor lung, with the former predominantly consisting of lung donor lymphocytes and the latter a mixture of lung and presumably transfusion source donor lymphocytes. The pretransplant donor lung exhibited no GVHD‐like pathology. CONCLUSION: This case demonstrates SOT‐GVHD, with the unusual feature of concomitant macrochimerism from transfusions. SOT‐GVHD likely predisposed this patient to the observed transfusion‐associated macrochimerism. However, the dissociation between transfusion‐attributable macrochimerism and attributable pathology is intriguing. Furthermore, the risk spectrum of transfusion‐associated macrochimerism and TA‐GVHD in solid organ transplant recipients with and without the complication of SOT‐GVHD is unknown and warrants further study.