Literature review of pediatric Erdheim-Chester disease (ECD) and mixed histiocytosis (Langerhans cell histiocytosis/ECD).

BACKGROUND AND OBJECTIVE: Langerhans cell histiocytosis (LCH) and Rosai-Dorfman disease (RDD) are more commonly observed in childhood; however, Erdheim-Chester disease (ECD) predominantly affects adults, making pediatric ECD extremely rare. To find out the incidence and characteristics of ECD in children, a review article was prepared. METHODS: A literature review was conducted to estimate the incidence of pediatric ECD and characterize its clinical features, using PubMed and Crossref, during 1990 to June 2026, with searched terms "Childhood or Pediatric", "Erdheim-Chester disease", "Mixed histiocytosis". KEY CONTENT AND FINDINGS: A total of 28 pediatric ECD cases were collected, which compared with previously reported pediatric ECD case series (Pegoraro et al., n=21; Romano et al., n=16). Based on these reports, it was estimated that more than 30 pediatric ECD cases have been described to date. Pediatric ECD appears to be characterized by relatively high rates of central nervous system involvement (53-67%) and mixed histiocytosis (20-38%). In addition, ophthalmologic involvements in the Yeager et al.'s study in 45% (adult 30%) of pediatric ECD should be recognized as an important manifestation in the eyes even in children. Regarding prognosis, most pediatric patients with ECD were reported as alive with disease (AWD) at the time of publication, suggesting a more favorable outcome than that observed in adult cases. CONCLUSIONS: Diagnosing ECD in children remains challenging; however, this rare entity should be considered in the differential diagnosis of pediatric histiocytosis, particularly in cases with central nervous system and ophthalmologic involvement.