# Hemophagocytic Lymphohistiocytosis in a Pediatric Lung Transplant Recipient

## TL;DR

This paper reports the first known case of a rare and severe immune disorder called hemophagocytic lymphohistiocytosis (HLH) in a child who received a lung transplant.

## Contribution

The paper presents the first documented pediatric case of HLH following lung transplantation and highlights the challenges in diagnosis and treatment.

## Key findings

- HLH occurred two months after lung transplantation in a previously healthy adolescent.
- The patient showed clinical improvement with dexamethasone monotherapy despite an unclear cause.
- Literature suggests HLH is rare but fatal in post-transplant patients, with most cases occurring within the first few months.

## Abstract

Hemophagocytic lymphohistiocytosis (HLH) is a rare complication of solid organ transplantation and is a syndrome of systemic hyperinflammation secondary to dysregulation of the inflammatory response, primarily involving lymphocytes and macrophages. It is often fatal and therefore early recognition and treatment are crucial. Among 11 adult cases of HLH in post‐lung transplant cases found in the literature, only one patient survived.

We report the first known pediatric case of HLH following lung transplantation. The patient, a previously healthy adolescent, developed end‐stage bullous lung disease secondary to acute respiratory distress syndrome (ARDS) and underwent bilateral lung transplantation. Two months posttransplant, he was admitted with an asymptomatic febrile illness of unclear etiology. By day four, evolving multiorgan dysfunction raised concern for HLH. Despite extensive infectious, autoimmune, and malignancy workups, no definitive trigger was identified. Treatment was initiated with dexamethasone monotherapy with subsequent clinical improvement and discharge 1 month later.

Solid organ transplantation appears to raise a patient's risk of developing HLH, although the underlying mechanisms are unclear. Literature review suggests patients are most likely to develop this complication within the first few months of transplantation, and a high index of suspicion must be maintained in those who present with a febrile illness of unclear etiology. Standard HLH treatment protocols may not be applicable to this patient population, and further studies are needed.