# Bile Duct Targeting or Preservation: Contrasting Liver Histology in Langerhans Cell Histiocytosis and Disseminated Juvenile Xanthogranuloma

## TL;DR

This paper compares liver damage patterns in two rare diseases, LCH and JXG, to improve diagnosis and treatment strategies.

## Contribution

The study highlights distinct liver histology patterns in LCH and JXG, impacting diagnosis and transplant outcomes.

## Key findings

- LCH causes bile duct destruction leading to cholestatic cirrhosis and sclerosing cholangitis.
- JXG preserves bile ducts despite histiocyte infiltration, showing a different liver pathology.
- BRAF inhibitors in LCH can cause granulomatous reactions mimicking disease recurrence after transplant.

## Abstract

Liver involvement by histiocytic and dendritic cell neoplasms signals high-risk disease, often necessitating closer monitoring and aggressive management. Severe cases may progress to liver failure, requiring transplantation. Liver involvement occurs in about one-third of patients with systemic juvenile xanthogranuloma (JXG) and 20% to 60% of pediatric patients with Langerhans cell histiocytosis (LCH), particularly in multiorgan disease. Tyrosine kinase inhibitors show promise in LCH treatment, but optimal timing for treatment cessation remains uncertain. We present 2 pediatric cases, 1 with LCH, and the other with disseminated JXG, along with a literature review emphasizing liver histopathology and transplant considerations. These cases highlight distinct histological patterns. In LCH, progressive bile duct destruction led to ductopenic cholestatic cirrhosis and secondary sclerosing cholangitis. In contrast, in the case of JXG, bile ducts remained intact despite being surrounded by histiocytes. In both, disease localization to larger, segmental portal tracts may reduce liver biopsy sensitivity. In LCH, BRAF inhibitor therapy triggered a granulomatous reaction that could mimic disease recurrence in the liver graft. Other histiocytoses typically spare the bile ducts and do not cause biliary cirrhosis. Recognizing these distinct infiltration patterns can aid diagnosis and management.