Epithelial to mesenchymal transition in endomyocardial biopsies from orthotopic heart transplant recipients.

Epithelial to mesenchymal transition (EMT) occurs when cells lose morphological features of epithelial cells, such as cell-to-cell adhesion, and gain features of mesenchymal cells, including elongation and flattening. These cells also lose expression of epithelial immunohistochemical markers. In this report, we present a 55-year-old Caucasian male patient who underwent orthotopic heart transplant and immunosuppressant therapy with tacrolimus and mycophenolic acid. Seven and a half months later, an endomyocardial biopsy revealed a hypercellular, atypical lesion. Evaluation was negative for acute cellular rejection and post-transplant lymphoproliferative disorder. Histopathologic features and immunohistochemical stains were consistent with EMT. We subsequently identified four additional cases of EMT in patients who underwent orthotopic heart transplantation and received a similar immune suppression regimen. EMTs have been reported to occur in lung and kidney allografts; however, this is the first known report describing this entity in a heart transplant recipient.