RESUMO
Acute tubular necrosis (ATN) is the most important and frequent cause of acute kidney injury (AKI). Controversy exists concerning the role of renal biopsy in the evaluation of ATN prognosis. We aim in our study to evaluate the role of renal biopsy for the detection of recovery and progression and rate of recovery of ATN. The study was designed to include all biopsies with the diagnosis in ATN in adults >21-year-old, from January 2016 to December 2018. Biopsies were recruited retrospectively and were reviewed by three pathologists and quantitated. Four histological ATN features were evaluated. Flattening cells, distension or dilatation, debris, and vacuolation and for each a score were attributed as follows: 0 = less than 5% of section, 1 = 6%-25%, 2 = 26%-50%, 3 = >50%. Thirty-five patients with 35 renal biopsies were analyzed. Flattening was seen <5% in nine patients, 6%-25% in 15 patients, 26%-50% in six patients. and >50% in five patients. Dilatation was seen <5% in 11 patient, 6%-25% in 10 patients, 26%-50% seen in six patients, and >50% in eight patients. The presence of debris was seen in <5% in 12 patients, 6%-25% in 12 patients, 26%-50% seen in six patients, and >50% seen in five patient. Vacuolation was seen in 5% in eight patients, 6%-25% in 14 patients, 26%-50% in seven patients, and >50% in six patients. It was found that flattening <5% and dilatation <5% and dilatation >50% in renal biopsy are the good indicators for recovery and good prognosis of cases of ATN, in addition debris <5% and >50% and vacuolation <5% are also good indicators for recovery and good prognosis of cases of ATN. On the other hand, flattening from 6% to 25% and from 26% to 50%, dilatation from 6% to 25%, debris from 26% to 50% and vacuolation >50% are also indicators for delayed recovery and poor prognosis of cases of ATN. Renal biopsy in AKI with the diagnosis of ATN with scoring system of flattening, dilatation, debris, and vacuolation can point to indication of recovery or progression of these cases.