1 | INTRODUCTION
Juvenile xanthogranuloma (JXG), the most common form of non-Langerhans
cell histiocytosis (LCH), is thought to arise from dermal dendrocytes or
macrophages. The majority of patients with the disease present primarily
with skin lesions, which usually regress spontaneously. However, some
patients develop extracutaneous lesions, with or without cutaneous
lesions (i.e., systemic JXG); sometimes, these lesions can progress
rapidly and can reduce quality of life, or even become life-threatening,
despite aggressive LCH-oriented chemotherapy.1,2Similar to other histiocytic disorders such as LCH and Erdheim–Chester
disease (ECD), patients with systemic JXG often harbor somatic mutations
in the mitogen-activated protein kinase (MAPK) pathway genes, most
notably BRAF.3
LCH affects the central nervous system, manifesting primarily as
diabetes insipidus, or more rarely as neurodegenerative disease (ND).
LCH-associated ND, characterized by progressive radiological
abnormalities of the cerebellum, basal ganglia, and pons, as well as
cerebellar dysfunction accompanied by cognitive impairment and
behavioral disturbance, can develop many years after treatment for
LCH.4 Involvement of multiple organ systems,
particularly the pituitary gland, skin, base skull, or orbit bone
involvement, and presence of the BRAF V600E mutation, are risk factors
for developing LCH-associated ND.5
ND also occurs in patients with ECD;4 however, there
is no report about ND in patients with JXG. Here, we report two cases of
JXG who presented with radiological abnormalities similar to those
observed for LCH-associated ND.