Maximal Change Disease

Introduction: Minimal change disease (MCD) accounts for the majority of cases of nephrotic syndrome in children and a minority of cases in adults. We report a case of MCD in a middle-aged patient with severe acute kidney injury (AKI) requiring dialysis who did not respond to steroids but eventually improved with rituximab. Case Description: A 64 year old male with a history of mantle cell lymphoma (in remission) presented with reduced urinary output. Physical examination was notable for anasarca. Labs showed acute kidney injury (creatinine 4.31 mg/dL, baseline 1), hypoalbuminemia (albumin 2.7 g/dL), and nephrotic range proteinuria (urine protein creatinine ratio 22 mg/mg). His AKI worsened over several days as evidenced by rising creatinine to a peak of 9.1 mg/dL, volume expansion and anuria for which hemodialysis was initiated. A renal biopsy was performed, demonstrating podocytopathy with global foot process effacement, consistent with minimal change disease. A workup for recurrent lymphoma was unrevealing. He was treated with a course of prednisone 60 mg daily followed by a taper. After no improvement in renal function was seen with prednisone, he was considered steroid-refractory, and treatment with rituximab was started. He received two infusions. He remained dialysis dependent at discharge following a two month hospital admission but was subsequently weaned off dialysis with recovery of renal function two months later. Discussion: AKI in MCD has been reported in approximately 20-30% of adult cases, some of whom may require dialysis. The pathophysiology of AKI in MCD is usually related to acute tubular necrosis. Interestingly, there was no tubular necrosis seen on biopsy for this patient. It was unclear as to whether the history of lymphoma was a contributing factor to this patient's presentation considering there was no evidence of lymphoma recurrence. However, a retrospective review examining MCD in non-Hodgkin lymphoma found that while they most often occur simultaneously, MCD may be diagnosed before or after non-Hodgkin lymphoma. Rituximab is considered to be an effective therapy for adult patients with frequently relapsing MCD, especially for those at risk of developing adverse effects of steroids. The mechanism by which rituximab improves outcomes in MCD is not fully understood, but the depletion of CD20 expressing cells using rituximab in MCD has led to the hypothesis that B cells have a pathogenic role in the condition.