Herein, we report a case of acute kidney injury (AKI) due to diarrhea-induced acute tubular necrosis (ATN) in a patient with nephrotic syndrome secondary to biopsy-proven collapsing focal and segmental glomerulosclerosis (FSGS). The clinical picture mimicked rapidly progressive glomerulonephritis (RPGN) and motivated pulse therapy with methylprednisolone and cyclophosphamide. The case presentation is followed by a brief overview of the epidemiology of AKI in nephrotic syndrome as well as a discussion of its risk factors and potential mechanisms involved.