A 27-years-old woman underwent cadaveric kidney transplantation for renal failure secondary to unknown cause. Her immediate posttransplant course was uneventful. Immunosuppression treatment was with cyclosporine A, mycophenolate mofetil, and prednisone. Three post-transplantation months she presented with an elevated serum creatinine: 3.0 mg/dL. She did not have previous rejection episodes. Proteinuria: 200 mg/dL; no hematuria. She did not have systemic symptoms.
Renal sonography did not show renal alterations; arterial and venous flow were normal.
With presumptive diagnosis of acute rejection, a renal biopsy was performed.
See the images.
Figure 1. H&E, X200.
Figure 2. H&E, X200.
Figure 3. H&E, X400.
Figure 4. H&E, X400.
Figure 5. H&E, X400.
Figure 6. H&E, X400. (The mitosis is not the more relevant feature)
Figure 7. H&E, X400.
Immunohistochemistry for C4d was negative.
What is your diagnosis?