Fine needle aspiration biopsy and cytology in renal transplantation.

Fine needle aspiration biopsy with cytology provides a useful and easily repeated method of obtaining cell samples from a grafted kidney, enabling a more accurate diagnosis of rejection. The technique is simple to perform and is minimally invasive. It is easily repeated, daily if necessary, to evaluate events within the graft and the response to therapy. In addition to the findings of rejection (high total corrected incremental score and activated lymphocytes), both cyclosporin toxicity and acute tubular necrosis can be diagnosed. In the patient with a non-functioning graft with acute tubular necrosis, repeated fine needle aspiration biopsy may reveal early rejection. In rare cases, unusual graft infections have also been diagnosed by means of fine needle aspiration biopsy.