# An Unusual Case of Immune Complex-Mediated Membranoproliferative Glomerulonephritis as Renal Manifestation of Idiopathic Hypereosinophilic Syndrome: A Case Report and Literature Review

## TL;DR

This case report describes a rare kidney complication in a patient with idiopathic hypereosinophilic syndrome.

## Contribution

The paper presents a rare renal manifestation of IHES as immune complex-mediated membranoproliferative glomerulonephritis.

## Key findings

- A young patient with IHES developed nephrotic syndrome due to immune complex-mediated glomerulonephritis.
- Renal involvement in IHES is uncommon and often presents with non-specific symptoms.
- The case highlights the importance of considering renal biopsy in IHES patients with kidney dysfunction.

## Abstract

Background: Idiopathic hypereosinophilic syndrome (IHES) is a disorder characterized by abnormal and persistent peripheral blood hypereosinophilia (eosinophil count ≥ 1.5 × 109/L and ≥10% eosinophils) with duration ≥ 6 months, associated organ damage, and/or dysfunction attributable to tissue eosinophilic infiltrate of unknown cause. IHES affects different organs such as the heart, lungs, nervous system, and skin, with renal involvement being rare in this condition. Case Presentation: We present a case of a young patient with IHES and immune complex-mediated membranoproliferative glomerulonephritis with nephrotic syndrome, as a rare renal manifestation. We discuss the clinical, analytical, and histopathologic renal and hematologic features, comparing them with other reported cases in the literature.