Frozen-section analysis of allograft renal biopsy specimens. Reliable histopathologic data for rapid decision making.

Rapid tissue diagnosis during acute events associated with renal transplantation is often necessary to permit immediate decisions regarding initiation or modification of therapy. To achieve this, we performed frozen section analyses with cryoprotected alcoholic Bouin's-fixed tissue, which permits evaluation within 2.5 hours. During a 30-month period, 200 allograft biopsies were performed; 68 frozen sections were obtained when deemed necessary by the clinical team. We compared frozen-section diagnoses with those following regular evaluation of the biopsy specimen. Agreement in diagnoses occurred in 61 (88.4%) of 69 specimens. Acute rejection was the dominant diagnosis (n = 39); others were acute tubular necrosis, cyclosporine toxicity, chronic rejection, and infection. Major misdiagnoses included acute vascular processes (three capillary and/or venous thromboses and one vascular inflammation); acute cellular rejection was missed in two cases, reflecting a sampling error. Secondary diagnoses not of immediate therapeutic importance were detected in seven frozen sections and missed in nine. These included chronic glomerulopathies, nephrosclerosis, and mild chronic rejection. Although acute vascular phenomena may be difficult to recognize in frozen sections, we conclude that allograft biopsy frozen-section analysis is a valuable part of the care of transplant recipients.