Evaluation of cyclosporine nephrotoxicity by renal transplant fine needle aspiration

Fine needle aspiration is a relatively safe, minimally invasive technique for morphologic evaluation of intragraft events in renal transplant recipients. We assessed the usefulness of this technique in the diagnosis of acute cyclosporine nephrotoxicity (NT). Two aspirate features considered indicative of NT were examined; tubular cell cytoplasmic isometric vacuolization (IV) and isolated graft lymphocytosis. Fifty-six adequate aspirates from 22 patients receiving cyclosporine were evaluated by the method of Hayry and von Willebrand. Retrospectively, four groups were identified for the purpose of this study: A, greater than 50% tubular cell population with IV (N = 11); B, less than 50% tubular cell population with IV (N = 15); C, graft lymphocytosis without IV (N = 15); D, normal aspirates (N = 15). A retrospective clinical diagnosis of cyclosporine NT was present at the time of ten aspirations in Group A (91%) and one each in Groups B (7%) and C (7%, P less than 0.001). No patients with aspirates in Group D had NT. The remaining aspirates were from patients with multiple clinical diagnoses. Plasma cyclosporine levels did not correlate with IV or graft lymphocytosis. Serum creatinine levels were higher in patients from Group A as compared with Group D (P less than 0.03). We conclude that not all patients treated with cyclosporine or diagnosed with clinical cyclosporine NT demonstrate IV or lymphocytosis in graft aspirates. However, when isometric vacuolization occurs in greater than 50% of tubular cells, acute cyclosporine NT must be considered strongly. Isolated graft lymphocytosis is a nonspecific finding.