Introduction
Juvenile xanthogranuloma (JXG) is classified as a histiocytosis that is
generally diagnosed on the basis of the presence of cutaneous nodules in
infancy. It has been considered benign and could undergo spontaneous
regression without therapy.1 However, some patients
with systemic JXG, particularly patients with central nervous system
(CNS) involvement, might have severe neurological
sequelae.2 Conventional chemotherapy based on
Langerhans cell histiocytosis (LCH) have been applied for these severe
cases,2 but the response rate remains unclear. In
addition, adverse events and late complications induced by anticancer
drugs should be avoided in paediatric patients as much as possible,
especially in neonates. Recently, BRAF V600E mutation and recurrent
kinase fusions, including BRAF, NTRK and anaplastic lymphoma kinase
(ALK), including KIF5B-ALK fusion, have been identified in histiocytic
neoplasms.3,4. We present the case of a patient with
systemic JXG with KIF5B-ALK fusion detected by next-generation
sequencing (NGS) panel -based comprehensive genome profiling (CGP) for
solid tumours, in whom CNS lesions had caused neurological disorders.
There has been no report about ALK inhibitor for an infant case of
histiocytosis.