Clinical Characteristics and Treatment Outcomes of Myeloid Sarcoma in Children: The Experience of the Polish Pediatric Leukemia and Lymphoma Study Group

Abstract

IntroductionMyeloid sarcoma (MS) is an extramedullary malignant tumor composed of immature myeloid cells. It occurs in patients with acute myeloid leukemia (AML), myelodysplastic syndrome (MDS), or chronic myeloid leukemia (CML). MS may coincide with disease diagnosis or precede bone marrow involvement by months or even years; it can also represent the extramedullary manifestation of a relapse (1, 2).AimThe aim of this study is to describe clinical characteristics of children diagnosed with MS in Poland as well as to analyze diagnostic methods, treatment, and outcomes including overall survival (OS), relapse-free survival (RFS), and event-free survival (EFS). The study also attempted to identify factors determining treatment outcomes.PatientsThe study group comprised 43 patients (F=18, M=25) aged 0-18 years (median age, 10.0 years; mean age, 8.8 years) diagnosed with MS based on tumor biopsy and immunohistochemistry or identification of underlying bone marrow disease and extramedullary tumor according to imaging findings.MethodsThe clinical data and diagnostic and therapeutic methods used in the study group were analyzed. A statistical analysis of the treatment outcomes was conducted with STATISTICA v. 13 (StatSoft, Inc., Tulsa, OK, USA) and analysis of survival curves was conducted with MedCalc 11.5.1 (MedCalc Software, Ostend, Belgium). Statistical significance was considered at p<0.05.ResultsIn the study group, MS was most frequently accompanied by AML. The most common site of involvement was skin, followed by orbital region. Skin manifestation of MS was more common in the age group <10 years. The most frequent genetic abnormality was the t(8;21)(q22;q22) translocation. The 5-year OS probability (pOS), 5-year RFS probability (pRFS), and 5-year EFS probability (pEFS) were 0.67 ± 0.08, 0.79 ± 0.07, and 0.65 ± 0.08, respectively. In patients with isolated MS and those with concurrent bone marrow involvement by AML/MDS, pOS values were 0.56 ± 0.12 and 0.84 ± 0.09 (p=0.0251), respectively, and pEFS values were 0.56 ± 0.12 and 0.82 ± 0.08 (p=0.0247), respectively. In patients with and without the t(8;21)(q22;q22) translocation, pEFS values were 0.90 ± 0.09 and 0.51 ± 0.14 (p=0.0490), respectively.ConclusionsMS is a disease with a highly variable clinical course. Worse treatment outcomes were observed in patients with isolated MS compared to those with concurrent bone marrow involvement by AML/MDS. Patients with the t(8;21)(q22;q22) translocation were found to have significantly higher pEFS. MS location, age group, chemotherapy regimen, surgery, and/or radiotherapy did not have a significant influence on treatment outcomes. Further exploration of prognostic factors in children with MS is indicated.

Clinical characteristics, pathology features and outcomes of pediatric myeloid sarcoma: A retrospective case series

“…Patients with orbital MS mostly presented with AML M2 and M5 subtypes, and AML M5 subtype have a higher initial white blood cell count. These are consistent with previous reports ( 3 , 5 , 9 , 11 ).…”

“…According to the single-center data of 11 children diagnosed with MS, the most common subtype was MS accompanied by AML, which supported the previous literature ( 9 – 11 ). Approximately 6.7%–12% of childhood AML patients had MS at diagnosis ( 12 – 15 ).…”

Successful Treatment of Pediatric Acute Myeloid Leukemia Presenting with Hyperbilirubinemia Secondary to Myeloid Sarcoma: A Case Report

“…The most common mutation and translocation described in MS are mutated NPM1 and t(8:21), respectively [ 22 , 23 ]. There is uncertainty regarding the value of t(8;21) in MS, even though it has a favorable prognostic significance for AML [ 24 ]. Inversion-16 translocation is associated with MS, particularly in abdominal sites [ 25 ].…”

“…Analysis of 345 patients with isolated MS in the SEER database showed that patients with MS had a better survival rate than those without MS [ 31 ]. Sambroska et al reported worse outcome in patients with isolated MS compared to patients with MS with AML (56% and 84%, respectively) [ 24 ]. Other studies considered MS a poor prognostic factor with lower EFS and OS [ 32 , 33 ].…”

Primary myeloid sarcoma in an infant with an NRAS mutation

“…One review of all pediatric myeloid sarcomas in Poland demonstrated an additional 12 pediatric isolated MS cases. 16 Our patient relapsed at the end of therapy, presenting us with a treatment dilemma as no therapeutic guidelines for relapsed MS exist.…”