\documentclass[10pt]{article}

\usepackage{fullpage}
\usepackage{setspace}
\usepackage{parskip}
\usepackage{titlesec}
\usepackage[section]{placeins}
\usepackage{xcolor}
\usepackage{breakcites}
\usepackage{lineno}
\usepackage{hyphenat}





\PassOptionsToPackage{hyphens}{url}
\usepackage[colorlinks = true,
            linkcolor = blue,
            urlcolor  = blue,
            citecolor = blue,
            anchorcolor = blue]{hyperref}
\usepackage{etoolbox}
\makeatletter
\patchcmd\@combinedblfloats{\box\@outputbox}{\unvbox\@outputbox}{}{%
  \errmessage{\noexpand\@combinedblfloats could not be patched}%
}%
\makeatother


\usepackage{natbib}




\renewenvironment{abstract}
  {{\bfseries\noindent{\abstractname}\par\nobreak}\footnotesize}
  {\bigskip}

\titlespacing{\section}{0pt}{*3}{*1}
\titlespacing{\subsection}{0pt}{*2}{*0.5}
\titlespacing{\subsubsection}{0pt}{*1.5}{0pt}


\usepackage{authblk}


\usepackage{graphicx}
\usepackage[space]{grffile}
\usepackage{latexsym}
\usepackage{textcomp}
\usepackage{longtable}
\usepackage{tabulary}
\usepackage{booktabs,array,multirow}
\usepackage{amsfonts,amsmath,amssymb}
\providecommand\citet{\cite}
\providecommand\citep{\cite}
\providecommand\citealt{\cite}
% You can conditionalize code for latexml or normal latex using this.
\newif\iflatexml\latexmlfalse
\providecommand{\tightlist}{\setlength{\itemsep}{0pt}\setlength{\parskip}{0pt}}%

\AtBeginDocument{\DeclareGraphicsExtensions{.pdf,.PDF,.eps,.EPS,.png,.PNG,.tif,.TIF,.jpg,.JPG,.jpeg,.JPEG}}

\usepackage[utf8]{inputenc}
\usepackage[greek,english]{babel}



\usepackage{float}








\begin{document}

\title{Philadelphia chromosome-like B-lymphoblastic leukemia and disseminated
juvenile xanthogranulomatosis with shared KRAS mutation}



\author[1]{Jinjun Cheng}%
\author[1]{Nikolaos Svoronos}%
\author[1]{Miao Pan}%
\author[2]{Shelby Smith}%
\author[1]{Anant Vatsayan}%
\author[1]{David Jacobsohn}%
\author[1]{Birte Wistinghausen}%
\affil[1]{Children’s National Hospital}%
\affil[2]{Children's National Hospital Center for Cancer and Blood Disorders}%


\vspace{-1em}



  
  \date{March 14, 2025}


\begingroup
\let\center\flushleft
\let\endcenter\endflushleft
\maketitle
\endgroup





\selectlanguage{english}
\begin{abstract}
Secondary histiocytoses are exceedingly rare and knowledge about
pathophysiology and treatment is limited. We report the first known case
of Philadelphia chromosome -like - B-lymphoblastic leukemia complicated
by disseminated juvenile xanthogranuloma in an adolescent salvaged
successfully with targeted MEK inhibition.%
\end{abstract}%



\sloppy


\textbf{Philadelphia chromosome-like B-acute lymphoblastic leukemia and
disseminated juvenile xanthogranulomatosis with shared KRAS mutation}

Jinjun Cheng\textsuperscript{2,3,4*}, Nikolaos
Svoronos\textsuperscript{1,3,4*}, Miao Pan \textsuperscript{2,4}, Shelby
Smith,\textsuperscript{1} Anant Vatsayan, \textsuperscript{1,3,4} David
Jacobsohn, \textsuperscript{1,3,4} Birte
Wistinghausen\textsuperscript{1,3,4}

\begin{enumerate}
\tightlist
\item
  Center for Cancer and Blood Disorder, Children's National Hospital
\item
  Department of Pathology and Laboratory Medicine, Children's National
  Hospital
\item
  Center for Cancer and Immunology Research, Children's National
  Hospital
\item
  George Washington University School of Medicine and Health Sciences,
  Washington, DC
\end{enumerate}

\textbf{* Both authors contributed equally and share first authorship}

\textbf{Correspondence to:}

Jinjun Cheng, MD, PhD

Pathology and Laboratory Medicine Division

Children's National Hospital

Washington, DC 20010-2970

Tel: 202-476-4311

Fax: 202-476-4030

Email: jcheng2@childrensnational.org

Birte Wistinghausen, MD

Center for Cancer and Blood Disorders

Children's National Hospital

111 Michigan Ave NW

Washington, DC 20010

Email: bwistingha@childrensnational.org

\textbf{Word Count:} 1150

\textbf{Tables:} 0

\textbf{Figures:} 2

\textbf{Running title:} Trametinib for Ph-like ALL with disseminated JXG

\textbf{Key words:} Trametinib, KRAS, CRLF2, JXG, Ph-like ALL

\textbf{List of abbreviations:}\selectlanguage{english}
\begin{longtable}[]{@{}ll@{}}
\toprule
Abbreviation & Full term\tabularnewline
\midrule
\endhead
LCH & Langerhans cell histiocytosis\tabularnewline
JXG & Juvenile xanthogranuloma\tabularnewline
ALL & Acute lymphoblastic leukemia\tabularnewline
HLH & Hemophagocytic lymphohistiocytosis\tabularnewline
MEK & Mitogen-activated protein kinase kinase\tabularnewline
GVHD & Graft-versus-host disease\tabularnewline
COG & Children Oncology Group\tabularnewline
WHO & World Health Organization\tabularnewline
ICC & International consensus classification\tabularnewline
\bottomrule
\end{longtable}

\emph{TITLE}

\textbf{Philadelphia chromosome-like B-lymphoblastic leukemia and
disseminated juvenile xanthogranulomatosis with shared KRAS mutation}

\emph{ABSTRACT}

Secondary histiocytoses are exceedingly rare and knowledge about
pathophysiology and treatment is limited. We report the first known case
of Philadelphia chromosome -like - B-lymphoblastic leukemia complicated
by disseminated juvenile xanthogranuloma in an adolescent salvaged
successfully with targeted MEK inhibition.

\emph{INTRODUCTION}

Philadelphia chromosome - like acute lymphoblastic leukemia (Ph-like
ALL) is defined by a gene expression profile similar to
\emph{BCR::ABL1}ALL.\textsuperscript{1} and associated with chemotherapy
resistance and high risk of relapse.\textsuperscript{2} The four major
subgroups of Ph-like ALL consist of \emph{CRLF2} rearrangements,
\emph{ABL} -class fusions, \emph{EPOR} rearrangements, and
\emph{JAK2}rearrangements.\textsuperscript{3} In addition, somatic NTRK3
and RAS signaling pathway mutations (IL-7R, KRAS, NRAS) have been
identified in a subset of Ph-like ALL.\textsuperscript{4}

Histiocytic disorders are characterized by aberrant accumulation of
phagocytes frequently with activating somatic mutations in RAS-MAPK
pathway genes.\textsuperscript{5} Juvenile Xanthogranuloma (JXG)
typically presents as a benign self-resolving non-Langerhans-cell
histiocytic cutaneous proliferation . Clinical behavior and histology of
disseminated JXG overlap with malignant histiocytosis (or histiocytic
sarcoma) that can arise as a primary neoplasm or be associated with
precursor hematopoietic malignancies, such as juvenile myelomonocytic
and acute lymphoblastic leukemia.\textsuperscript{5-11} Secondary
histiocytic neoplasms and their associated hematologic neoplasms share
common genetic aberrations suggesting clonal
divergence.\textsuperscript{10}

Here we report the first known case of a pediatric patient with
refractory Ph-like B-ALL complicated by disseminated JXG and
hemophagocytic lymphohistiocytosis (HLH) treated with targeted therapy.
This case provides unique insight into the drivers of both Ph-like B-ALL
and JXG and illustrates novel use of a targeted MEK inhibitor.

\emph{CASE REPORT}

A 12-year-old previously healthy Hispanic male initially presented with
two weeks of fever, fatigue, and weight loss. Initial labs showed
leukocytosis of 549,000 cells/mcL with 96\% B-lymphoblasts (CD45 dim+,
CD34+, CD19+, CD10+, CD20+, HLADR+, CD9+, CD22+, CD24+, CD38+, CD58+,
cytoCD79a+, cytoCD22+, and TdT+). Fluorescent in situ hybridization
(FISH) revealed a cryptic translocation Y;14 resulting
in\emph{CRLF2::IGH} rearrangement, consistent with a diagnosis of
Ph-like B-ALL. Further molecular analysis detected a KRAS G12D mutation
but was negative for other mutations. Due to age, elevated WBC, and CNS3
disease, he was classified high-risk and treated with a standard four
drug induction chemotherapy regimen (prednisone, vincristine,
daunorubicin, and pegaspargase) and weekly intrathecal methotrexate as
previously published.\textsuperscript{12} At end of induction, he was in
morphological remission but had minimal residual disease (MRD) of 0.02\%
by flow cytometry. Consolidation chemotherapy was started with
cyclophosphamide, cytarabine, mercaptopurine.

During consolidation, he developed numerous reddish nodules on his face
and scalp that were biopsied (Figure 1A). Immunohistochemical analysis
demonstrated histiocytic proliferations positive for CD68 and Factor
XIIIa and negative for CD1a, S100, and BRAF V600E (Figure 2), consistent
with JXG. Due to persistent non-neutropenic fever with anemia and
thrombocytopenia, consolidation chemotherapy was held, and repeat bone
marrow (BM) biopsy showed 18\% B-lymphoblasts by flow cytometry. He
received two doses each of vincristine and low-dose IV methotrexate in
preparation for leukapheresis for potential chimeric antigen receptor
T-cell therapy which could not be performed due to rapid clinical
deterioration with fever, cytopenias, low fibrinogen, high ferritin, and
elevated soluble IL-2R consistent with secondary HLH. He started on
dexamethasone and anakinra. Computer tomography (CT) demonstrated
hepatosplenomegaly with numerous small, ill-defined hypodensities in the
spleen,liver (Figure 1B) and an additional pulmonary lesion. A repeat BM
biopsy showed disseminated JXG but absent B-lymphoblasts by flow
cytometry (\textless{}0.01\%). Somatic gene sequencing of cutaneous JXG
was significant for two variants activating MAPK pathway (BRAF G469R and
KRAS G12D) as well as an MTOR S2215Y variant. Germline genetic testing
was negative.

As patient's B-lymphoblasts and JXG cells shared the KRAS G12D mutation,
we decided to target the MAPK pathway using the MEK inhibitor
(trametinib) while the patient was critically ill. With initiation of
trametinib, patient's clinical status rapidly improved including
hematopoietic recovery along with improvement of cutaneous and systemic
JXG lesions by exam and imaging (Figure 1C). He received a course of
blinatumomab with trametinib followed by TCR alpha beta/CD 19 depleted
maternal haploidentical hematopoietic cell transplant (HCT) with a
conditioning regimen of total body irradiation with cranial boost,
cyclophosphamide, thiotepa, and rabbit anti-thymocyte globulin.
Follow-up BM biopsies showed decreasing NGS MRD positivity to a low of 4
dominant clonal cells per million nucleated cells (Figure 2H). The
patient was in continuous remission of ALL, HLH, and JXG, until his
death 300 days after HCT due to multiorgan injury, severe hemorrhagic
shock from gastrointestinal bleeding and disseminated polymicrobial
infections secondary to complications of steroid refractory
graft-versus-host disease (GVHD).

\emph{DISCUSSION}

To the best of our knowledge, this is the first report of disseminated
JXG in pediatric Ph-like B-ALLwhere identification of a shared mutation
was targeted therapeutically. A few cases of JXG associated with
pediatric B- or T-ALL have been reported in the
literature.\textsuperscript{6,9,13-17} Therefore, there is a lack of
understanding and treatment guidelines about this rare, and complex
clinical condition. As shown in our case and literature, unusual skin
lesions during therapy for leukemia should undergo a timely and thorough
workup.

Histiocytoses including JXG frequently contain mutations in the RAS-MAPK
pathway genes that can be therapeutically targeted. Our case is unique
in that the same KRAS G12D mutation was found in both JXG and
B-lymphoblasts, which adds to prior studies suggesting a clonal
relationship between histiocytic disorders and ALL. A similar phenomenon
has been reported in malignant histiocytic sarcoma and Langerhans cell
histiocytosis diverging from prior T or B-ALL precursors that shared
common genetic changes, such as \emph{CDKN2A} deletion,
\emph{MYC}translocation, or \emph{RAS} mutations.\textsuperscript{20}
Mutations in RAS-MAPK signaling pathway genes have been identified in a
subset of ALL\textsuperscript{21}, especially relapsed or refractory
ALL. Whether trametinib would have a therapeutic benefit for these
patients is unknown. In our patient, this novel approach stabilized him,
resolved HLH, and allowed him to proceed to curative therapies. In
addition, the identical clonal IgH- or TCR\selectlanguage{greek}γ-\selectlanguage{english}gene rearrangements have
been reported in the histiocytic neoplasms and leukemia or
lymphomas.\textsuperscript{22}In our patient, the polymerase chain
reaction (PCR) for IgH gene rearrangement was clonal in the skin biopsy
of JXG, consistent with a common clonal origin of patient's B-ALL and
JXG. We were not able to obtain NGS testing of IgH, IgK and IgL on the
skin biopsy; but because of the known clonal rearrangement of IgH by
PCR, we hypothesized that NGS of IgH, IgK and IgL sequences could be
used for MRD monitoring of both JXG and B-ALL in the BM as previously
reported in a single patient.\textsuperscript{7} During follow-up, we
suspected that the residual clones identified by NGS were more likely
JXG than B-ALL due to the absence of B-lymphoblasts by flow cytometry
based MRD techniques.

In summary, we report the first patient with Ph-like B-ALL complicated
by disseminated JXG due to a shared KRAS G12D who achieved a remission
with targeted therapy using a MEK inhibitor and was able to proceed to
HCT.

\emph{References}

1. Downing JR, Shannon KM. Acute leukemia: a pediatric
perspective.\emph{Cancer Cell.} 2002;2(6):437-445.

2. Harvey RC, Tasian SK. Clinical diagnostics and treatment strategies
for Philadelphia chromosome-like acute lymphoblastic
leukemia.\emph{Blood Adv.} 2020;4(1):218-228.

3. Roberts KG, Reshmi SC, Harvey RC, et al. Genomic and outcome analyses
of Ph-like ALL in NCI standard-risk patients: a report from the
Children's Oncology Group. \emph{Blood.} 2018;132(8):815-824.

4. Roberts KG, Li Y, Payne-Turner D, et al. Targetable kinase-activating
lesions in Ph-like acute lymphoblastic leukemia. \emph{N Engl J
Med.}2014;371(11):1005-1015.

5. McClain KL, Bigenwald C, Collin M, et al. Histiocytic
disorders.\emph{Nat Rev Dis Primers.} 2021;7(1):73.

6. Castro EC, Blazquez C, Boyd J, et al. Clinicopathologic features of
histiocytic lesions following ALL, with a review of the
literature.\emph{Pediatr Dev Pathol.} 2010;13(3):225-237.

7. Fenu EM, Margolskee E, Pillai V. Transdifferentiation of
B-lymphoblastic leukemia to histiocytic sarcoma after
immunotherapy.\emph{Am J Hematol.} 2023;98(8):E216-E218.

8. Kato M, Seki M, Yoshida K, et al. Genomic analysis of clonal origin
of Langerhans cell histiocytosis following acute lymphoblastic
leukaemia. \emph{Br J Haematol.} 2016;175(1):169-172.

9. Pawinska-Wa Sikowska K, Cwiklinska M, Wyrobek E, et al. Disseminated
Juvenile Xanthogranuloma and Hemophagocytic Lymphohistiocytosis
Developed During Treatment of Acute Lymphoblastic Leukemia: Case
Report.\emph{Front Oncol.} 2020;10:921.

10. Feldman AL, Minniti C, Santi M, Downing JR, Raffeld M, Jaffe ES.
Histiocytic sarcoma after acute lymphoblastic leukaemia: a common clonal
origin. \emph{Lancet Oncol.} 2004;5(4):248-250.

11. Newman H, MacFarland SP, Brodeur GM, et al. B-cell acute
lymphoblastic leukemia and juvenile xanthogranuloma in a patient with
ETV6 thrombocytopenia and leukemia predisposition syndrome: novel
clinical presentation and perspective. \emph{Haematologica.} 2023.

12. Salzer WL, Burke MJ, Devidas M, et al. Toxicity associated with
intensive postinduction therapy incorporating clofarabine in the very
high-risk stratum of patients with newly diagnosed high-risk
B-lymphoblastic leukemia: A report from the Children's Oncology Group
study AALL1131. \emph{Cancer.} 2018;124(6):1150-1159.

13. Aparicio G, Mollet J, Bartralot R, et al. Eruptive juvenile
xanthogranuloma associated with relapsing acute lymphoblastic
leukemia.\emph{Pediatr Dermatol.} 2008;25(4):487-488.

14. Bailey KM, Castle VP, Hummel JM, Piert M, Moyer J, McAllister-Lucas
LM. Thalidomide therapy for aggressive histiocytic lesions in the
pediatric population. \emph{J Pediatr Hematol Oncol.}2012;34(6):480-483.

15. Cheon E, Yang S, Han JH, Lee KC, Park JE. Systemic Juvenile
Xanthogranuloma Involving the Bone Marrow, Multiple Bones, and the Skin
That Developed During Treatment of Acute Lymphoblastic Leukemia in
Remission State. \emph{Pediatr Dev Pathol.} 2018;21(5):489-493.

16. Perez-Becker R, Szczepanowski M, Leuschner I, et al. An aggressive
systemic juvenile xanthogranuloma clonally related to a preceding T-cell
acute lymphoblastic leukemia. \emph{Pediatr Blood
Cancer.}2011;56(5):859-862.

17. Rotte JJ, de Vaan GA, Koopman RJ. Juvenile xanthogranuloma and acute
leukemia: a case report. \emph{Med Pediatr Oncol.} 1994;23(1):57-59.

18. Morier P, Merot Y, Paccaud D, Beck D, Frenk E. Juvenile chronic
granulocytic leukemia, juvenile xanthogranulomas, and neurofibromatosis.
Case report and review of the literature. \emph{J Am Acad
Dermatol.}1990;22(5 Pt 2):962-965.

19. Paxton CN, O'Malley DP, Bellizzi AM, et al. Genetic evaluation of
juvenile xanthogranuloma: genomic abnormalities are uncommon in solitary
lesions, advanced cases may show more complexity. \emph{Mod
Pathol.}2017;30(9):1234-1240.

20. Egan C, Lack J, Skarshaug S, et al. The mutational landscape of
histiocytic sarcoma associated with lymphoid malignancy. \emph{Mod
Pathol.} 2021;34(2):336-347.

21. Irving J, Matheson E, Minto L, et al. Ras pathway mutations are
prevalent in relapsed childhood acute lymphoblastic leukemia and confer
sensitivity to MEK inhibition. \emph{Blood.} 2014;124(23):3420-3430.

22. Feldman AL, Berthold F, Arceci RJ, et al. Clonal relationship
between precursor T-lymphoblastic leukaemia/lymphoma and Langerhans-cell
histiocytosis. \emph{Lancet Oncol.} 2005;6(6):435-437.

\emph{FIGURE LEGENDS}

\textbf{Figure 1:} During consolidation patient developed generalized
hyperpigmented cutaneous nodules with central ulceration (A). CT imaging
prior to treatment with trametinib demonstrating hepatosplenomegaly with
multiple hypodensities, possibly JXG infiltrates (B). Patient after
treatment with trametinib showing improvement in cutaneous JXGs (C).

\textbf{Figure 2:} Pre-B ALL at diagnosis, showing lymphoblasts in the
peripheral blood (A; Wright stain x 1000), with
\emph{CRLF2::IGH}rearrangement (insert: CRLF2(Xp22/Yp11)(proximal
5'=green/distal 3'=red), FISH). During consolidation chemotherapy, the
BM biopsy showed residual B-ALL (B; hematoxylin and eosin x100; insert
PAX5 immunohistochemical stain x100), and no significant histiocytic
proliferation seen. At this time, the patient started to present
multiple skin lesions with the biopsy showing diffuse histiocytic
proliferation with absence of cytological atypia; mitoses are rare (C;
hematoxylin and eosin x100). CD68 and Factor XIIIa immunohistochemical
stains show strong reactivity in histiocytic cells (D and E; brown
reaction product, x 100). PCR showed clonal banding patterns in JXG, by
both immunoglobulin and T-cell receptor gene rearrangement studies (not
shown). A few weeks later, the repeated bone marrow biopsy revealed
replacement by JXG (F; hematoxylin and eosin, x 200), diffusely positive
for Factor XIIIa (G; brown reaction product, x200). PAX5 immunostaining
was negative and flow MRD was negative for residual lymphoblasts (not
shown). The results of molecular MRD follow up by using clono-SEQ assay
(H). The flow cytometry MRD and immunostaining of PAX5 on core biopsy
remained negative (data not shown).\selectlanguage{english}
\begin{figure}[H]
\begin{center}
\includegraphics[width=0.70\columnwidth]{figures/Figure-2/Figure-2}

\end{center}
\end{figure}\selectlanguage{english}
\begin{figure}[H]
\begin{center}
\includegraphics[width=0.70\columnwidth]{figures/Picture-1/Picture-1}

\end{center}
\end{figure}

\selectlanguage{english}
\FloatBarrier
\end{document}

