Discussion
Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare myeloid
malignancy with non-pruritic, violaceous, and papulo-nodular skin
lesions, as well as the involvement of the bone marrow and lymph nodes.
The WHO’s 2016 classification of hematological neoplasms recognizes
BPDCN as an unique acute leukemia entity. BPDCN has been reported in
infants and children, even though it primarily affects older persons
with a median age of 65 years. It is typically characterized by
involvement of the skin that rapidly evolves and compromise organs such
as bone marrow, lymph nodes, viscera, and, to a lesser extent, the
central nervous system (CNS)[3].
With just a few research reports to date, the etiology and
pathophysiology of BPDCN are largely unclear. BPDCN is frequently linked
with a complicated karyotype, numerous tumor suppressor gene deletions,
and abnormalities in the DNA methylation or chromatin remodeling
pathways.[4]. In the case of Congenital Blastic Plasmacytoid
Dendritic Cell Neoplasm, Kiriko Tokuda et al. described an infant with
CLTC-ALK Fusion, which is considered a primary event[5].
In various epithelial and myeloid cells, the lysine-specific
methyltransferase 2C (KMT2C/MLL3) is a possible tumor suppressor. KMT2C
has also played a tumor suppressor role in acute myeloid leukemia (AML)
and urothelial carcinogenesis in mice[6-7]. Its involvement in BPDCN
carcinogenesis, however, is mainly unknown. Toya T et al. reported the
first MLL-ENL rearrangement in a 45-year-old male patient in
2012[8]. In 2015, Naery Yang et al. said the first pediatric case of
BPDCN with a KMT2A (MLL)-MLLT1 rearrangement[9]. Four
juvenile patients of BPDCN with KMT2C gene mutation were recently
described by Chan Liao et al., emphasizing the possible critical roles
of KMT2 family genes in BPDCN[10].
Our study reports the first newborn BPDCN patient with KMT2C gene
duplication. It is crucial to understand the pathophysiology of this
rare disease, and more research into the gene expression profile and
pathogenesis of BPDCN in pediatric patients may drastically enhance
prognosis.