Immunophenotypic characteristics of juvenile myelomonocytic leukaemia and their relation with the molecular subgroups of the disease

Abstract

The diagnosis of juvenile myelomonocytic leukaemia (JMML) is based on clinical, laboratory and molecular features but immunophenotyping [multiparametric flow cytometry (MFC)] has not been used routinely. In the present study, we describe the flow cytometric features at diagnosis with special attention to the distribution of monocytic subsets and the relation between MFC and molecular subgroups. MFC was performed with an eight-colour platform based on Euroflow. We studied 33 JMML cases. CD34 + /CD117 + /CD13 + cells >2% was found in 25 cases, and 51Á5% presented an aberrant expression of CD7. A decrease of CD34 + /CD19 + /CD10 + cells was seen in eight cases and in four they were absent. The granulocytic population had a decreased side scatter in 29 cases. Bone marrow monocytic precursors were increased in 28 patients, with a decrease in classical monocytes (median 80Á7%) and increase in CD16 + (intermediate and nonclassical). A more pronounced increase in myeloid CD34 + cells was seen in patients with Neurofibromatosis type 1 (NF1) and tyrosine-protein phosphatase non-receptor type 11 (PTPN11), with aberrant CD7 expression in four of six and 10/12 patients respectively. Thus, JMML shows an immunophenotypic profile similar to myelodysplastic syndromes, and a different monocyte subset distribution when compared with chronic MML. MFC proved to be an important diagnostic tool that can help in differential diagnosis with other clonal diseases with monocytosis.

Phenotypic profiling of CD34⁺ cells by advanced flow cytometry improves diagnosis of juvenile myelomonocytic leukemia

“…These aspects are currently being investigated and they may also contribute to a better understanding of the genetic heterogeneity of JMML patients. 24 , 26 , 39 …”

“…These aspects are currently being investigated and they may also contribute to a better understanding of the genetic heterogeneity of JMML patients. 24,26,39 However, given the limited sample size of our series and the possibility that RAS cases with lower scores could be RALD and not JMML, the power to assess phenotypic-genotypic associations should be considered with caution.…”

“…Despite this, Oliveira et al have recently shown a significant decrease of T lymphocytes and the presence of several phenotypic abnormalities within CD34 + cells of JMML patients including the aberrant expression of CD7 in the majority of CD34 + CD117 + CD13 + cells, associated with a decrease or complete lack of CD19 + CD10 + B-cell precursors, 24 similarly to what has been described in adults with myelodysplastic syndrome (MDS) and/or myeloproliferative neoplasm (MPN). 25 , 26 …”

“…Despite this, Oliveira et al have recently shown a significant decrease of T lympho-cytes and the presence of several phenotypic abnormalities within CD34 + cells of JMML patients including the aberrant expression of CD7 in the majority of CD34 + CD117 + CD13 + cells, associated with a decrease or complete lack of CD19 + CD10 + B-cell precursors, 24 similarly to what has been described in adults with myelodysplastic syndrome (MDS) and/or myeloproliferative neoplasm (MPN). 25,26 Since 2012, the EuroFlow consortium has developed fully standardized approaches for immunophenotyping of hematological malignancies, including validated antibody panels, standardized sample preparation protocols, gating strategies and innovative (smart) data analysis and software tools embedded with artificial intelligence, to prospectively classify individual patients against a predefined reference database of normal/reactive and disease associated groups of subjects. 27 However, these approaches have never been applied for the diagnosis of JMML.…”

Droplet digital PCR: An effective method for monitoring and prognostic evaluation of minimal residual disease in JMML

“…Consequently, traditional multiparameter flow cytometry (MFC) is less practical in JMML monitoring. 9 Common therapeutic interventions post-HSCT are guided by sequential chimerism studies using short tandem repeat polymerase chain reaction (STR-PCR), which reflect donor cell engraftment and offer predictive value for relapse. 10,11 However, the sensitivity of STR-PCR is only approximately 5%, which highlights the need for more sensitive methods to enhance relapse prediction.…”