# Case Report: Successful avoidance of etoposide for primary hemophagocytic lymphohistiocytosis-induced multiple organ dysfunction syndrome using emapalumab

## TL;DR

An infant with a severe immune condition was successfully treated with emapalumab instead of etoposide, avoiding further organ damage.

## Contribution

This case demonstrates successful etoposide avoidance and potential benefits of high-dose emapalumab in primary HLH.

## Key findings

- The patient's organ dysfunction improved after emapalumab treatment.
- Genetic analysis confirmed pathogenic mutations in the perforin gene.
- High-dose emapalumab may be beneficial in primary HLH without etoposide.

## Abstract

We describe the case of an infant who presented with simple rhinovirus/enterovirus bronchiolitis whose condition worsened with rapid progression to multiple organ dysfunction syndrome (MODS). The patient was presumed to have either primary or secondary hemophagocytic lymphohistiocytosis (HLH), and treatment was initiated using dexamethasone, anakinra, and intravenous immunoglobulin to modulate the immune system. Due to the organ dysfunction, the use of etoposide was avoided and instead, emapalumab, an interferon gamma antagonist, was administered at a dose of 6 mg/kg. The patient's organ failure improved, and the levels of inflammatory markers decreased. The flow cytometry analysis revealed that cytotoxic cells lacked perforin expression, and subsequent genetic analysis confirmed homozygous pathogenic mutations in the perforin gene. This case highlights the potential avoidance of etoposide in cases of primary HLH, the possible benefit of an elevated initial dose of emapalumab, and the contribution offered by a multi-specialty team approach to complex diagnosis.