Clinicopathological and molecular characteristics of pediatric type
Pediatric follicular lymphoma (PTFL) is one of the rare pediatric-type
indolent B-cell lymphomas that clinicopathologically differs from adult
lymphoma. Accurate diagnosis of PTFL is essential to avoid
leak-diagnosis, misdiagnosis and overtreatment, but it is often
challenging. To improve the understanding of PTFL, we collected four
cases of PTFL, and analyzed the clinicopathological features,
differential diagnosis and molecular mutation characteristics of PTFL by
hematoxylin‑eosin stain, immunohistochemistry, polymerase chain reaction
(PCR), fluorescence in situ hybridization (FISH) and Next Generation
Sequencing (NGS). The relevant literature review was also performed.
Four PTFL patients were all male, aged 6, 18, 13 and 15 years, and St.
Jude were staged III. and I.. Microscopic results showed that the lymph
node structure was destroyed; the tumor follicles were enlarged and
irregular; medium-large blast-like cells with a consistent shape were
visible in tumor follicles, and the nucleus was round or oval; the
“starry sky” phenomenon was easy to discover. Tumor cells expressed
CD20, PAX-5, Bcl-6, CD10. None of the tumor cells expressed Bcl-2, CD3,
CD5, MUM-1, and CyclinD1. CD21 showed dilated growth of follicular
dendritic cell (FDC) mesh in tumor follicles. EBER were all negative.
FISH testing also showed negative Bcl-2 gene breaks in four cases. A
total of 12 related mutant genes including KMT2D, CD79B,
GNA13, MYD88, PCLO, TCF3, IRF8,
MAP2K1, FOXO1, POLE, INPP5D and FAT4 were detected
by NGS. Two of the four cases had IRF8 gene mutation, and one
case detected a dual mutation of the MAP2K1 gene. Our data
reviewed the unique clinicopathological features and molecular
mutational characteristics of PTFL, consolidated the understanding of
PTFL, and identified other rare mutant genes, which may further
contribute to the study of the molecular mechanism and differential
diagnosis of PTFL.