Langerhans cell histiocytosis 

Rare disease involving clonal proliferation and migration of dendritic antigen-presenting histiocytes. 

More common in females and usually affects children between 1 and 3 years of age

Among adults the incidence is ten times less with a wide range of ages affected with a mean in the thirties and only 10% over 55

LCH can be stratified in two major categories: 

Single-system is further subdivided into single site (unifocal bone, skin) and multiple site (multifocal bone, skin, or lymph nodes). 

Multisystem, defined as involvement of two or more organs with or without dysfunction, is subdivided into “low-risk” and “high-risk” groups. Absence of “risk” organs (liver, lungs, spleen, and hematopoietic system) involvement characterizes “low-risk” patients (approx. 20%) and is associated with a good prognosis. “High-risk” patients (80%) have at least one risk organ involved and a high mortality rate

Frequency of liver involvement is known to be high (19–60%) in children and bears a poor prognosis. Among adults, liver involvement is rare and is poorly understood, though it is an important cause of morbidity and mortality.