Spectrum of Neuroimaging Features of Histiocytosis Syndromes in Children

Histiocytosis syndromes are a group of disorders characterized by abnormal accumulation and infiltration of organs by mononuclear phagocytic cells. The 2021 World Health Organization CNS tumor classification reorganized this group and included only 5 histiocytosis types that show frequent CNS involvement. Langerhans cell histiocytosis is the most common and well-known member of the group. However, it is also important to be familiar with the classic imaging characteristics of the remaining 4 subtypes. Although in some cases histiocytosis can be strongly considered with typical findings on neuroimaging, in other cases, the imaging findings will be nonspecific and pose a diagnostic challenge. The differential diagnosis can be narrowed at such times when information such as the patient’s clinical presentation and age is considered. This review presents imaging examples with current literature to comprehensively describe the neuroimaging spectrum of CNS involvement by histiocytoses.

Learning Objective: To discuss neuroimaging findings of Langerhans and non-Langerhans cell histiocytosis in children, with illustrative case examples