A diagnostic conundrum: acute interstitial nephritis due to armodafinil versus acute cellular rejection in a renal transplant recipient--a case report.

Acute interstitial nephritis is a well-recognized cause of acute kidney injury in native kidneys. While the most common etiology being drug-induced, other causes are infectious, autoimmune, and idiopathic forms of disease. Drug-induced acute interstitial nephritis is not only uncommon in renal transplant recipients but is difficult to diagnose as it mimics acute cellular rejection histologically. We have described herein a renal transplant recipient with acute kidney injury to highlight the difficulties to distinguish acute interstitial nephritis from acute cellular rejection.