# CNS erythroblastic sarcoma: a potential emerging pediatric tumor type characterized by NFIA::RUNX1T1/3 fusions

Arnault Tauziède-Espariat, Lucille Lew-Derivry, Samuel Abbou, Alice Métais, Gaëlle Pierron, Stéphanie Reynaud, Julien Masliah-Planchon, Cassandra Mariet, Lauren Hasty, Volodia Dangouloff-Ros, et al.

<figure><img src="image_1.png" /></figure>

## To cite this version:

Arnault Tauziède-Espariat, Lucille Lew-Derivry, Samuel Abbou, Alice Métais, Gaëlle Pierron, et al. CNS erythroblastic sarcoma: a potential emerging pediatric tumor type characterized by NFIA::RUNX1T1/3 fusions. Acta Neuropathologica Communications, 2024, 12 (1), pp.12. 10.1186/s40478-023-01708-5. http://dx.doi.org/10.1186/s40478-023-01708-5

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## CASE REPORT

## Open Access

<figure><img src="image_1.png" /></figure>

# CNS erythroblastic sarcoma: a potential emerging pediatric tumor type characterized by NFIA::RUNX1T1/3 fusions

Arnault Tauziède-Espariat¹,²*†, Lucille Lew-Derivry³, Samuel Abbou⁴, Alice Métais¹,²†, Gaëlle Pierron⁵,⁶, Stéphanie Reynaud⁶, Julien Masliah-Planchon⁶, Cassandra Mariet¹, Lauren Hasty¹, Volodia Dangouloff-Ros⁷,⁸, Nathalie Boddaert⁷,⁸, Marie Csanyi⁹, Aude Aline-Fardin¹⁰, Claire Lamaison¹¹, Fabrice Chrétien¹, Kévin Beccaria¹², Stéphanie Puget¹³ and Pascale Varlet¹,²

### Abstract

Erythroblastic sarcoma (ES) (previously called chloroma or granulocytic sarcoma) are rare hematological neoplasms characterized by the proliferation of myeloid blasts at extramedullary sites, and primarily involve the skin and soft tissue of middle-aged adults. ES may be concomitant with or secondary to myeloid neoplasms (mostly acute myeloid leukemia (AML)) or in isolated cases (de novo) without infiltration of the bone marrow by blasts. ES share cytogenetic and molecular abnormalities with AML, including *RUNX1T1* fusions. Some of these alterations seem to be correlated with particular sites of involvement. Herein, we report an isolated erythroblastic sarcoma with *NFIA::RUNX1T1* located in the central nervous system (CNS) of a 3-year-old boy. Recently, two pediatric cases of CNS MS with complete molecular characterization have been documented. Like the current case, they concerned infants (2 and 3 years-old) presenting a brain tumor (pineal involvement) with leptomeningeal dissemination. Both cases also harbored a *NFIA::RUNX1T3* fusion. ES constitutes a diagnostic challenge for neuropathologists because it does not express differentiation markers such as CD45, and may express CD99 which could be confused with CNS Ewing sarcoma. CD43 is the earliest pan-hematopoietic marker and CD45 is not expressed by erythroid lineage cells. E-cadherin (also a marker of erythroid precursors) and CD117 (expressed on the surface of erythroid lineage cells) constitute other immunhistochemical hallmarks of ES. The prognosis of patients with ES is similar to that of other patients with AML but de novo forms seem to have a poorer prognosis, like the current case. To conclude, pediatric ES with *NFIA::RUNX1T1/3* fusions seem to have a tropism for the CNS and thus constitute a potential pitfall for neuro-pathologists. Due to the absence of circulating blasts and a DNA-methylation signature, the diagnosis must currently be made by highlighting the translocation and expression of erythroid markers.

**Keywords** Myeloid sarcoma, NFIA::RUNX1T1, Central nervous system, CNS leukemia

<footnote>†Arnault Tauziède-Espariat and Alice Métais contributed equally to this work.</footnote>

<footnote>*Correspondence:
Arnault Tauziède-Espariat
a.tauziede-espariat@ghu-paris.fr
Full list of author information is available at the end of the article</footnote>
CASE REPORT

Open Access

<figure><img src="image_3.png" /></figure>

# CNS erythroblastic sarcoma: a potential emerging pediatric tumor type characterized by NFIA::RUNX1T1/3 fusions

Arnault Tauziède-Espariat¹,²*†, Lucille Lew-Derivry³, Samuel Abbou⁴, Alice Métais¹,²†, Gaëlle Pierron⁵,⁶, Stéphanie Reynaud⁶, Julien Masliah-Planchon⁶, Cassandra Mariet¹, Lauren Hasty¹, Volodia Dangouloff-Ros⁷,⁸, Nathalie Boddaert⁷,⁸, Marie Csanyi⁹, Aude Aline-Fardin¹⁰, Claire Lamaison¹¹, Fabrice Chrétien¹, Kévin Beccaria¹², Stéphanie Puget¹³ and Pascale Varlet¹,²

## Abstract

Erythroblastic sarcoma (ES) (previously called chloroma or granulocytic sarcoma) are rare hematological neoplasms characterized by the proliferation of myeloid blasts at extramedullary sites, and primarily involve the skin and soft tissue of middle-aged adults. ES may be concomitant with or secondary to myeloid neoplasms (mostly acute myeloid leukemia (AML)) or in isolated cases (de novo) without infiltration of the bone marrow by blasts. ES share cytogenetic and molecular abnormalities with AML, including *RUNX1T1* fusions. Some of these alterations seem to be correlated with particular sites of involvement. Herein, we report an isolated erythroblastic sarcoma with *NFIA::RUNX1T1* located in the central nervous system (CNS) of a 3-year-old boy. Recently, two pediatric cases of CNS MS with complete molecular characterization have been documented. Like the current case, they concerned infants (2 and 3 years-old) presenting a brain tumor (pineal involvement) with leptomeningeal dissemination. Both cases also harbored a *NFIA::RUNX1T3* fusion. ES constitutes a diagnostic challenge for neuropathologists because it does not express differentiation markers such as CD45, and may express CD99 which could be confused with CNS Ewing sarcoma. CD43 is the earliest pan-hematopoietic marker and CD45 is not expressed by erythroid lineage cells. E-cadherin (also a marker of erythroid precursors) and CD117 (expressed on the surface of erythroid lineage cells) constitute other immunhistochemical hallmarks of ES. The prognosis of patients with ES is similar to that of other patients with AML but de novo forms seem to have a poorer prognosis, like the current case. To conclude, pediatric ES with *NFIA::RUNX1T1/3* fusions seem to have a tropism for the CNS and thus constitute a potential pitfall for neuro-pathologists. Due to the absence of circulating blasts and a DNA-methylation signature, the diagnosis must currently be made by highlighting the translocation and expression of erythroid markers.

**Keywords** Myeloid sarcoma, NFIA::RUNX1T1, Central nervous system, CNS leukemia

<footnote>†Arnault Tauziède-Espariat and Alice Métais contributed equally to this work.</footnote>

<footnote>*Correspondence:
Arnault Tauziède-Espariat
a.tauziede-espariat@ghu-paris.fr
Full list of author information is available at the end of the article</footnote>
**Introduction**

Erythroblastic sarcoma (ES) (previously called chlo-
roma or granulocytic sarcoma) are rare hematological
neoplasms characterized by the proliferation of myeloid
blasts at extramedullary sites, and primarily involve the
skin and soft tissue of middle-aged adults [1]. ES may be
concomitant with or secondary to myeloid neoplasms
(mostly acute myeloid leukemia (AML)) or in isolated
cases (de novo) without infiltration of the bone marrow
by blasts [1]. ES share cytogenetic and molecular abnor-
malities with AML, including *RUNX1* fusions [1, 2].
Some of these alterations seem to be correlated with par-
ticular sites of involvement (such as *RUNX1::RUNX1T1*
fusions for pediatric orbital tumors) [1].

Case presentation

Herein, we report an isolated erythroblastic sarcoma
located in the central nervous system (CNS) of a previ-
ously healthy 3-year-old boy, who suddenly presented
with epileptic seizures and post-critic left hemiplegia.
Magnetic resonance imaging (MRI) revealed a right fron-
tal lesion associated with leptomeningeal dissemination
(Fig. 1a-c). A biopsy of the lesion showed an undifferenti-
ated proliferation composed of sheets of large cells with
hyperchromatic nuclei, prominent nucleoli, brisk mitotic
activity and apoptotic bodies (Fig. 1d). INI1 and BRG1
stainings were maintained and there was no expression of
Lin28A, CD34, glial (GFAP and Olig2), neuronal (MAP2,
NeuN, synaptophysin), melanocytic (SOX10, HMB45),
myogenic (desmin and myogenin), or lymphoid (CD45,
CD3 and CD20) markers (Fig. 1e). The MIB1 labeling
index was greater than 90% (Fig. 1f). There was no immu-
noreactivity for BCOR, NUT, CD99, or ETV4. DNA-
methylation analysis was unable to classify the tumor. A
cytological study of the cerebrospinal fluid (CSF) showed
300 tumoral cells/mm³. The complete blood count was
normal and the bone marrow failed to reveal any blas-
tic proliferation. Because the RNA-sequencing analy-
sis revealed the presence of a *NFIA::RUNX1T1* fusion
(Fig. 2), a final diagnosis of ES was suggested. Comple-
mentary immunohistochemical analyses showed the
expression of CD117 and CD43, but no immunopositivity

for E-cadherin was observed (Fig. 1g-i). The patient pre-
sented a neurological impairment with decreased con-
sciousness and therefore received steroids and a first line
of empiric chemotherapy adapted to sarcoma, based on
the first histological results before the RNA sequencing
was available (vincristin, doxorubicin, cyclophosphamide,
and then etoposide and ifosfamide) [3]. This treatment
was rapidly efficient for the consciousness disorders.
When the final diagnosis was available, the treatment
was adapted and the patient was treated in accordance
with the Myechild 01 Trial with mitoxantrone (12 mg/
m²×3) and cytarabine (100 mg/m²×4). Because of the
tumor's rapid local progression (Fig. 1j-l), and symp-
toms of intracranial hypertension (IH), the treatment was
intensified with higher dose of cytarabine (12 g/m² total
dose) but was inefficient. Intratechal (IT) chemotherapy
injections were not possible due to the IH. A subtotal
resection was performed, and an Ommaya reservoir was
put into place for intratechal injections of cytarabine,
methotrexate and steroids. Despite 7 IT injections and
a high intravenous dose of Methorexate associated with
Erwinase injections, the CSF was still blastic and the sub-
sequent progressive disease led to a rapid decline. The
patient expired three months after symptoms began.

**Discussion and conclusions**

Acute erythroid leukemias (AELs) represent only 1.2% of pediatric AML [4]. CNS localizations of ES are exceptionally rare in the literature, with a subset of them being secondary locations of myeloid neoplasms (AML) [2]. Recently, two pediatric cases of CNS ES with complete molecular characterization have been documented [5, 6]. Like the current case, they concerned infants (2 and 3 years-old) presenting a brain tumor (pineal involvement) with leptomeningeal dissemination [5, 6]. Both cases also harbored a *NFIA::RUNX1T3* fusion [5, 6], whereas the current case presented a *NFIA::RUNX1T1* fusion, also previously described in one pediatric abdominal ES case [7]. *NFIA* belongs to the NF1 family of transcription factors which is required for erythroid differentiation. *RUNX1T1* (also named as *CBFA2T1*) and *RUNX1T3* (also known as *CBFA2T3*) are part of the MTG (Myeloid Transcription Genes) family of transcriptional regulators

(See figure on next page.)

**Fig. 1** Radiological and histopathological features the case Axial T2-weighted (a, d), axial (b, e) and coronal (c, f) T1-weighted images after gadolinium injection a, b, c: initial MRI, showing a thick linear enhancement within the right frontal lobe, and important peritumoral edema (high-T2-weighted signal), associated with thick and diffuse leptomeningeal enhancement. Frontal tumor enhancement showed restricted diffusion (image not shown). d, e, f: The follow-up MRI, 3 months after partial surgery, showing an increased solid tumor volume and larger peritumoral edema. The biopsy highlighted a dense proliferation composed of sheets of undifferentiated cells with numerous mitotic figures (g HPS, magnification × 400). Tumor cells were immunonegative for CD45 which highlighted some normal lymphocytes (h magnification × 400). Diffuse expression of CD43 (i magnification × 400) and CD117 (j magnification × 400). No immunoexpression for E-cadherin (k magnification 400x). High MIB1 labeling index (l magnification × 400). Scale bars represent 50 µm. HPS: Hematoxylin Phloxin Saffron
## Introduction

Erythroblastic sarcoma (ES) (previously called chlo-
roma or granulocytic sarcoma) are rare hematological
neoplasms characterized by the proliferation of myeloid
blasts at extramedullary sites, and primarily involve the
skin and soft tissue of middle-aged adults [1]. ES may be
concomitant with or secondary to myeloid neoplasms
(mostly acute myeloid leukemia (AML)) or in isolated
cases (de novo) without infiltration of the bone marrow
by blasts [1]. ES share cytogenetic and molecular abnor-
malities with AML, including *RUNX1* fusions [1, 2].
Some of these alterations seem to be correlated with par-
ticular sites of involvement (such as *RUNX1::RUNX1T1*
fusions for pediatric orbital tumors) [1].

## Case presentation

Herein, we report an isolated erythroblastic sarcoma
located in the central nervous system (CNS) of a previ-
ously healthy 3-year-old boy, who suddenly presented
with epileptic seizures and post-critic left hemiplegia.
Magnetic resonance imaging (MRI) revealed a right fron-
tal lesion associated with leptomeningeal dissemination
(Fig. 1a-c). A biopsy of the lesion showed an undifferenti-
ated proliferation composed of sheets of large cells with
hyperchromatic nuclei, prominent nucleoli, brisk mitotic
activity and apoptotic bodies (Fig. 1d). INI1 and BRG1
stainings were maintained and there was no expression of
Lin28A, CD34, glial (GFAP and Olig2), neuronal (MAP2,
NeuN, synaptophysin), melanocytic (SOX10, HMB45),
myogenic (desmin and myogenin), or lymphoid (CD45,
CD3 and CD20) markers (Fig. 1e). The MIB1 labeling
index was greater than 90% (Fig. 1f). There was no immu-
noreactivity for BCOR, NUT, CD99, or ETV4. DNA-
methylation analysis was unable to classify the tumor. A
cytological study of the cerebrospinal fluid (CSF) showed
300 tumoral cells/mm³. The complete blood count was
normal and the bone marrow failed to reveal any blas-
tic proliferation. Because the RNA-sequencing analy-
sis revealed the presence of a *NFIA::RUNX1T1* fusion
(Fig. 2), a final diagnosis of ES was suggested. Comple-
mentary immunohistochemical analyses showed the
expression of CD117 and CD43, but no immunopositivity

for E-cadherin was observed (Fig. 1g-i). The patient pre-
sented a neurological impairment with decreased con-
sciousness and therefore received steroids and a first line
of empiric chemotherapy adapted to sarcoma, based on
the first histological results before the RNA sequencing
was available (vincristin, doxorubicin, cyclophosphamide,
and then etoposide and ifosfamide) [3]. This treatment
was rapidly efficient for the consciousness disorders.
When the final diagnosis was available, the treatment
was adapted and the patient was treated in accordance
with the Myechild 01 Trial with mitoxantrone (12 mg/
m²×3) and cytarabine (100 mg/m²×4). Because of the
tumor's rapid local progression (Fig. 1j-l), and symp-
toms of intracranial hypertension (IH), the treatment was
intensified with higher dose of cytarabine (12 g/m² total
dose) but was inefficient. Intratechal (IT) chemotherapy
injections were not possible due to the IH. A subtotal
resection was performed, and an Ommaya reservoir was
put into place for intratechal injections of cytarabine,
methotrexate and steroids. Despite 7 IT injections and
a high intravenous dose of Methorexate associated with
Erwinase injections, the CSF was still blastic and the sub-
sequent progressive disease led to a rapid decline. The
patient expired three months after symptoms began.

## Discussion and conclusions

Acute erythroid leukemias (AELs) represent only 1.2% of pediatric AML [4]. CNS localizations of ES are exceptionally rare in the literature, with a subset of them being secondary locations of myeloid neoplasms (AML) [2]. Recently, two pediatric cases of CNS ES with complete molecular characterization have been documented [5, 6]. Like the current case, they concerned infants (2 and 3 years-old) presenting a brain tumor (pineal involvement) with leptomeningeal dissemination [5, 6]. Both cases also harbored a *NFIA::RUNX1T3* fusion [5, 6], whereas the current case presented a *NFIA::RUNX1T1* fusion, also previously described in one pediatric abdominal ES case [7]. *NFIA* belongs to the NF1 family of transcription factors which is required for erythroid differentiation. *RUNX1T1* (also named as *CBFA2T1*) and *RUNX1T3* (also known as *CBFA2T3*) are part of the MTG (Myeloid Transcription Genes) family of transcriptional regulators

(See figure on next page.)

**Fig. 1** Radiological and histopathological features the case Axial T2-weighted (a, d), axial (b, e) and coronal (c, f) T1-weighted images after gadolinium injection a, b, c: initial MRI, showing a thick linear enhancement within the right frontal lobe, and important peritumoral edema (high-T2-weighted signal), associated with thick and diffuse leptomeningeal enhancement. Frontal tumor enhancement showed restricted diffusion (image not shown). d, e, f: The follow-up MRI, 3 months after partial surgery, showing an increased solid tumor volume and larger peritumoral edema. The biopsy highlighted a dense proliferation composed of sheets of undifferentiated cells with numerous mitotic figures (g HPS, magnification × 400). Tumor cells were immunonegative for CD45 which highlighted some normal lymphocytes (h magnification × 400). Diffuse expression of CD43 (i magnification × 400) and CD117 (j magnification × 400). No immunoexpression for E-cadherin (k magnification 400x). High MIB1 labeling index (l magnification × 400). Scale bars represent 50 µm. HPS: Hematoxylin Phloxin Saffron
<figure><img src="image_2.png" /><figcaption>**Fig. 1** (See legend on previous page.)</figcaption></figure>
<figure><img src="image_4.png" /><figcaption>**Fig. 1** (See legend on previous page.)</figcaption></figure>
<figure><img src="image_3.png" /><figcaption>**Fig. 2** Genetic features RNAseq analysis highlights a fusion between *NFIA* (pink) and *RUNX1T1* (blue) genes, respectively located on chr1p31.3 and chr8q21.3</figcaption></figure>

which repress gene transcription. ES constitutes a diagnostic challenge for neuropathologists because it does not express differentiation markers such as CD45, and may express CD99 which could be confused with CNS Ewing sarcoma [5, 6]. An extensive immunohistochemical analysis allows to eliminate high-grade gliomas, embryonal tumors (particularly atypical teratoid and rhabdoid tumor), sarcomas, CIC-rearranged, and primary rhabdomyosarcomas. CD43 is the earliest panhematopoietic marker and CD45 is not expressed by erythroid lineage cells [8]. E-cadherin (also a marker of erythroid precursors) and CD117 (expressed on the surface of erythroid lineage cells) constitute other immunohistochemical hallmarks of ES [5–7, 9]. The prognosis of patients with de novo ES seems to be pejorative but further reports are needed to conclude [1, 6].

To conclude, pediatric ES with *NFIA::RUNX1T1/3* fusions seem to have a tropism for the CNS and thus constitute a potential pitfall for neuropathologists. Due to the absence of circulating blasts and a DNA-methylation signature, the diagnosis must currently be made by highlighting the translocation and expression of erythroid markers.

**Author contributions**

ATE, LLD, SA, CM, KB, SP, VDR and NB compiled the MRI and clinical records; ATE, AME, AAF, MC, CL, FC and PV conducted the neuropathological examinations; GP, DG, and JMP conducted the molecular studies; ATE, LH, and PV drafted the manuscript; all authors reviewed the manuscript.

**Funding**

The authors declare that they have not received any funding.

**Declarations**

**Ethics approval and consent to participate**

This study was approved by GHU Paris Psychiatrie et Neurosciences, Sainte-Anne Hospital's local ethics committee.

**Competing interests**

The authors declare that they have no conflict of interest directly related to the topic of this article.

**Author details**

¹Department of Neuropathology, GHU Paris-Psychiatrie et Neurosciences, Sainte-Anne Hospital, 1, rue Cabanis, 75014 Paris, France. ²Inserm, UMR 1266, IMA-Brain, Institut de Psychiatrie et Neurosciences de Paris, Paris, France.

³Department of Hematology and Pediatric Oncology, Armand Trousseau Hospital, Paris, France. ⁴Children and Adolescent Oncology Department, INSERM U1015, Paris-Saclay University, Villejuif, France. ⁵Paris-Sciences-Lettres, Curie Institute Research Center, INSERM U830, Paris, France. ⁶Laboratory of Somatic Genetics, Curie Institute Hospital, Paris, France. ⁷Pediatric Radiology Department, Hôpital Necker Enfants Malades, AP-HP, Paris, France. ⁸UMR 1163, Institut Imagine and INSERM U1299, Université Paris Cité, Paris, France.

⁹Institute of Pathology, Centre de Biologie Pathologie, Lille University Hospital,
<figure><img src="image_5.png" /><figcaption>**Fig. 2** Genetic features RNAseq analysis highlights a fusion between *NFIA* (pink) and *RUNX1T1* (blue) genes, respectively located on chr1p31.3 and chr8q21.3</figcaption></figure>

which repress gene transcription. ES constitutes a diagnostic challenge for neuropathologists because it does not express differentiation markers such as CD45, and may express CD99 which could be confused with CNS Ewing sarcoma [5, 6]. An extensive immunohistochemical analysis allows to eliminate high-grade gliomas, embryonal tumors (particularly atypical teratoid and rhabdoid tumor), sarcomas, CIC-rearranged, and primary rhabdomyosarcomas. CD43 is the earliest panhematopoietic marker and CD45 is not expressed by erythroid lineage cells [8]. E-cadherin (also a marker of erythroid precursors) and CD117 (expressed on the surface of erythroid lineage cells) constitute other immunohistochemical hallmarks of ES [5–7, 9]. The prognosis of patients with de novo ES seems to be pejorative but further reports are needed to conclude [1, 6].

To conclude, pediatric ES with *NFIA::RUNX1T1/3* fusions seem to have a tropism for the CNS and thus constitute a potential pitfall for neuropathologists. Due to the absence of circulating blasts and a DNA-methylation signature, the diagnosis must currently be made by highlighting the translocation and expression of erythroid markers.

**Author contributions**

ATE, LLD, SA, CM, KB, SP, VDR and NB compiled the MRI and clinical records; ATE, AME, AAF, MC, CL, FC and PV conducted the neuropathological examinations; GP, DG, and JMP conducted the molecular studies; ATE, LH, and PV drafted the manuscript; all authors reviewed the manuscript.

**Funding**

The authors declare that they have not received any funding.

**Declarations**

**Ethics approval and consent to participate**

This study was approved by GHU Paris Psychiatrie et Neurosciences, Sainte-Anne Hospital's local ethics committee.

**Competing interests**

The authors declare that they have no conflict of interest directly related to the topic of this article.

**Author details**

¹Department of Neuropathology, GHU Paris-Psychiatrie et Neurosciences, Sainte-Anne Hospital, 1, rue Cabanis, 75014 Paris, France. ²Inserm, UMR 1266, IMA-Brain, Institut de Psychiatrie et Neurosciences de Paris, Paris, France.

³Department of Hematology and Pediatric Oncology, Armand Trousseau Hospital, Paris, France. ⁴Children and Adolescent Oncology Department, INSERM U1015, Paris-Saclay University, Villejuif, France. ⁵Paris-Sciences-Lettres, Curie Institute Research Center, INSERM U830, Paris, France. ⁶Laboratory of Somatic Genetics, Curie Institute Hospital, Paris, France. ⁷Pediatric Radiology Department, Hôpital Necker Enfants Malades, AP-HP, Paris, France. ⁸UMR 1163, Institut Imagine and INSERM U1299, Université Paris Cité, Paris, France.

⁹Institute of Pathology, Centre de Biologie Pathologie, Lille University Hospital,
59000 Lille, France. ¹⁰Department of Pathology, CHU de La Martinique, Fort-de-France, France. ¹¹Department of Pathology, Henri Mondor Hospital, APHP, Créteil, France. ¹²Department of Pediatric Neurosurgery, Necker Hospital, APHP, Université Paris Descartes, Sorbonne Paris Cite, 75015 Paris, France. ¹³Department of Pediatric Neurosurgery, CHU de La Martinique, Fort-de-France, France.

Received: 10 November 2023 Accepted: 10 December 2023

Published online: 19 January 2024

## References

1. WHO Classification of Tumours Editorial Board (2022) Haematolymphoid Tumours. Lyon (France): International Agency for Research on Cancer. WHO classification of tumours series, 5th Edn. Vol. 11

2. Yang Y, Shu Y, Tang Y, Zhao S, Jia Y, Ji J et al (2023) RNA sequencing of myeloid sarcoma, shed light on myeloid sarcoma stratification. Cancer Med 12(8):9156–9166

3. Grier HE, Krailo MD, Tarbell NJ, Link MP, Fryer CJH, Pritchard DJ et al (2003) Addition of ifosfamide and etoposide to standard chemotherapy for Ewing's sarcoma and primitive neuroectodermal tumor of bone. N Engl J Med 348(8):694–701

4. Chisholm KM, Heerema-McKenney AE, Choi JK, Smith J, Ries RE, Hirsch BA et al (2020) Acute erythroid leukemia is enriched in NUP98 fusions: a report from the children's oncology group. Blood Adv 4(23):6000–6008

5. Linnik Y, Pastakia D, Dryden I, Head DR, Mason EF (2020) Primary central nervous system erythroid sarcoma with NFIA-CBFA2T3 translocation: a rare but distinct clinicopathologic entity. Am J Hematol 95(11):E299-301

6. Liu H, Guinipero TL, Schieffer KM, Carter C, Colace S, Leonard JR et al (2020) De novo primary central nervous system pure erythroid leukemia/ sarcoma with t(1;16)(p31;q24) NFIA/CBFA2T3 translocation. Haematologica Avr 105(4):e194–e197

7. King RL, Siaghani PJ, Wong K, Edlefsen K, Shane L, Howard MT et al (2021) Novel t(1;8)(p31.3;q21.3) NFIA-RUNX1T1 translocation in an infant erythroblastic sarcoma. Am J Clin Pathol 156(1):129–138

8. Vodyanik MA, Thomson JA, Leukosialin Slukvin II. (2006) (CD43) defines hematopoietic progenitors in human embryonic stem cell differentiation cultures. Blood 108(6):2095–2105

9. Ohgami RS, Chisholm KM, Ma L, Arber DA (2014) E-cadherin is a specific marker for erythroid differentiation and has utility, in combination with CD117 and CD34, for enumerating myeloblasts in hematopoietic neoplasms. Am J Clin Pathol Mai 141(5):656–664

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<figure><img src="image_4.png" /></figure>
59000 Lille, France. ¹⁰Department of Pathology, CHU de La Martinique, Fort-de-France, France. ¹¹Department of Pathology, Henri Mondor Hospital, APHP, Créteil, France. ¹²Department of Pediatric Neurosurgery, Necker Hospital, APHP, Université Paris Descartes, Sorbonne Paris Cite, 75015 Paris, France. ¹³Department of Pediatric Neurosurgery, CHU de La Martinique, Fort-de-France, France.

Received: 10 November 2023 Accepted: 10 December 2023

Published online: 19 January 2024

## References

1. WHO Classification of Tumours Editorial Board (2022) Haematolymphoid Tumours. Lyon (France): International Agency for Research on Cancer. WHO classification of tumours series, 5th Edn. Vol. 11

2. Yang Y, Shu Y, Tang Y, Zhao S, Jia Y, Ji J et al (2023) RNA sequencing of myeloid sarcoma, shed light on myeloid sarcoma stratification. Cancer Med 12(8):9156–9166

3. Grier HE, Krailo MD, Tarbell NJ, Link MP, Fryer CJH, Pritchard DJ et al (2003) Addition of ifosfamide and etoposide to standard chemotherapy for Ewing's sarcoma and primitive neuroectodermal tumor of bone. N Engl J Med 348(8):694–701

4. Chisholm KM, Heerema-McKenney AE, Choi JK, Smith J, Ries RE, Hirsch BA et al (2020) Acute erythroid leukemia is enriched in NUP98 fusions: a report from the children's oncology group. Blood Adv 4(23):6000–6008

5. Linnik Y, Pastakia D, Dryden I, Head DR, Mason EF (2020) Primary central nervous system erythroid sarcoma with NFIA-CBFA2T3 translocation: a rare but distinct clinicopathologic entity. Am J Hematol 95(11):E299-301

6. Liu H, Guinipero TL, Schieffer KM, Carter C, Colace S, Leonard JR et al (2020) De novo primary central nervous system pure erythroid leukemia/ sarcoma with t(1;16)(p31;q24) NFIA/CBFA2T3 translocation. Haematologica Avr 105(4):e194–e197

7. King RL, Siaghani PJ, Wong K, Edlefsen K, Shane L, Howard MT et al (2021) Novel t(1;8)(p31.3;q21.3) NFIA-RUNX1T1 translocation in an infant erythroblastic sarcoma. Am J Clin Pathol 156(1):129–138

8. Vodyanik MA, Thomson JA, Leukosialin Slukvin II. (2006) (CD43) defines hematopoietic progenitors in human embryonic stem cell differentiation cultures. Blood 108(6):2095–2105

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