Pathological Non-rejection Findings in the Endomyocardial Biopsy

Heart transplant patients undergo regular endomyocardial biopsies to assess rejection, but a range of other histological findings need to be recognised and distinguished from cellular and antibody-mediated rejection. Some of these findings will require treatment in their own right; others need to be identified to avoid unnecessary treatment. Some changes in the early postoperative period should not be over-interpreted as early rejection. ‘Quilty’ effect is due to immunosuppressive therapy and resembles cellular rejection without the same clinical outcome. Later differentials include complications associated with transplantation such as infection, ischaemia due to cardiac allograft vasculopathy and lymphoproliferative disorders. Viral infection may produce a lymphocytic infiltrate difficult or even impossible to distinguish from cellular rejection. The primary disease may recur. Repeated biopsies themselves cause changes in the endomyocardium of the right ventricle; other structures such as valves, epicardium or liver fragments may be sampled. Pathologists should be aware of all these possibilities.