Background: A striped pattern of fibrosis has been described in the kidneys of patients undergoing long-term cyclosporine or tacrolimus therapy. This lesion is frequently misconstrued as being specific for drug toxicity.
Methods: We performed clinicopathologic correlation on 18 patients with striped fibrosis identified by reviewing 61 biopsies from kidney transplant recipients maintained with tacrolimus.
Results: Acute rejection was identified in 14 of 18 patients, chronic rejection in 9 of 18 patients, potential diabetic microvascular injury in 8 of 18, and pre-existing donor disease in 2 of 18. In only one patient could striped fibrosis be ascribed primarily to tacrolimus. Striped fibrosis could also be demonstrated in 6 of 10 late allograft biopsy specimens from patients maintained with only azathioprine, and 8 of 10 native biopsies from patients with advanced diabetes mellitus.
Conclusion: Multiple insults contribute to the pathogenesis of striped fibrosis in the kidney. This lesion can be attributed entirely to chronic drug toxicity in only a minority of allografts.