IMMUNOGLOBULIN A NEPHROPATHY WITH MINIMAL CHANGE DISEASE OVERLAP PRESENTING AS ACUTE KIDNEY INJURY REQUIRING HEMODIALYSIS

In IgA nephropathy (IgAN), the coexistence of nephrotic syndrome (NS) is associated with accelerated renal decline and unfavorable long-term outcomes. In contrast, IgAN with pathological features of minimal change disease (MCD-IgAN) is generally considered to have a favorable prognosis. To our knowledge, there have been no previous reports of MCD-IgAN requiring renal replacement therapy (RRT) for severe acute kidney injury (AKI). Here, we describe a case of MCD-IgAN who developed AKI that required temporary hemodialysis (HD), followed by renal recovery.

Case presentation: A 38-year-old man developed edema of the trunk and legs following cold-like symptoms, gained 6 kg within one week, and was admitted for fatigue. Vital signs were stable, but physical examination revealed marked pitting edema. Laboratory tests indicated severe NS with impaired renal function and markedly elevated tubular injury marker; proteinuria was highly selective. Renal biopsy was performed. Light microscopy of the biopsied sample showed diffuse mesangial matrix expansion with hemispherical deposits. Immunofluorescence analysis revealed mesangial IgA and C3 deposits, as well as KM55 (anti-Galactose-deficient IgA1 antibody) positivity, which colocalized with IgA. Electron microscopy revealed mesangial electron-dense deposits and partial podocyte foot-process effacement. MCD-IgAN was diagnosed. The patient was initially treated with high-dose corticosteroids, but oliguria persisted and temporary HD was required. Because nephrotic-range proteinuria remained, repeated courses of intravenous methylprednisolone were administered, and a calcineurin inhibitor was added. Renal function gradually improved allowing for the discontinuation of HD. Given persistent heavy proteinuria, low-density lipoprotein apheresis was subsequently initiated. After about five months of multidisciplinary therapy, serum albumin normalized and proteinuria decreased to levels consistent with partial remission.

Discussion: This case, with a well-supported diagnosis of MCD-IgAN including positive KM55 staining, presented with nephrotic-range proteinuria complicated by severe AKI requiring temporary HD. With intensive immunosuppressive therapy and adjunctive interventions, renal function gradually recovered, HD was discontinued, and proteinuria decreased to partial remission. Among the five previously reported cases of MCD-IgAN, KM55 staining was performed in three and was not consistently positive, and none developed HD-requiring AKI. By contrast, AKI in classic MCD (without IgA deposition) is associated with older male sex, severe hypoalbuminemia, massive proteinuria, hypertension, elevated tubular injury markers, and histologic evidence of tubular injury/interstitial edema. Our patient shared several of these risk factors—severe hypoalbuminemia, heavy proteinuria, and high tubular markers—and consequently developed AKI requiring temporary HD, despite the generally favorable prognosis of MCD-IgAN. These findings suggest that risk assessment and management strategies established for AKI in MCD should also be applied to patients with MCD-IgAN.

MCD-IgAN can present with severe AKI requiring RRT. Careful acute-phase management with attention to AKI risk is important even in this generally favorable phenotype.