Exfoliative cytology in the diagnosis of immunologic rejection in the transplanted kidney.

Urinary cytology was used in the study of 57 patients who received renal allografts. In general, there was close correlation between the cytologic and clinical evidence of rejection and, at least in some instances, rejection was detected cytologically prior to the onset of clinical signs and symptoms. A cytologic profile associated with rejection was established. This had as its main feature an increased number of tubular cells, particularly those that were small and degenerating. An associated background of cellular debris and casts was found to be of major significance. Intranuclear inclusions suggestive of viral infections were present in 15 patients. Cellular atypias caused by factors other than immunologic rejection were seen but none were of a malignant nature. It was considered of importance that the method described in this study could be carried out in a routine diagnostic cytopathology laboratory by cytotechnologists and cytopathologists who had received only a brief period of special training in the field of transplant cytology.