Clinicopathological and immunophenotypic features of early T cell precursor acute lymphoblastic leukaemia: A flow cytometry score for the initial diagnosis

Abstract

Objective: To assess the prevalence of early T precursor-acute lymphoblastic leukaemia (ETP-ALL), study its clinicopathological features and devise a 'flow score' based on immunophenotypic profiles. Material Methods:This was a retrospective study where clinical and laboratory data of all consecutive T-ALL cases were analysed to identify features differentiating ETP from non-ETP-ALL. The utility of a flow score based on the five commonly used markers in leukaemia panels for T-ALL (CD34, CD8, CD5, CD13 and CD33) was evaluated to differentiate ETP from non-ETP-ALL.Results: Early T precursor-acute lymphoblastic leukaemia constituted 24.2% (n = 29) of all T-ALL cases. It was significantly more common in adults (30.2%) as compared to paediatric (17.5%) patients (P = .046). The median age of presentation was significantly higher than the non-ETP group. (24 vs 19 years; P = .01). Patients with ETP-ALL usually presented with organomegaly, lymphadenopathy, lower levels of haemoglobin, total leucocyte count, peripheral blood blast proportion and LDH levels as compared to non-ETP-ALL. The majority of ETP-ALL cases had L2 morphology with a moderate amount of cytoplasm showing frequent blebbing. A flow score cutoff value of ≥3 on ROC curve analysis had a sensitivity and specificity of 100% and 94.6% respectively. Conclusion:Early T precursor-acute lymphoblastic leukaemia had unique clinical and laboratory features. The prevalence of this entity is more common in the adult population. A flow score based on a minimum of five widely used markers can confidently identify ETP-ALL and should be included in the primary panel of markers used for flow cytometric analysis.

Comparison of flowcytometry‐based scoring system for the diagnosis of early T precursor‐acute lymphoblastic leukemia

“…Our study population's median age of presentation at the time of diagnosis was 20 years (1–79 years), which concurs with the results in other studies reported in India. The median age noted by Chopra et al (2014) and Chandra et al (2021) was 22 and 24 years, respectively.…”

“…The overall prevalence among all acute leukemia cases at both centers was 3.6% (31/860). The existing data suggest a varying prevalence ranging between 5% and 47% (Bond et al, 2017; Chandra et al, 2021; Chopra et al, 2014; Coustan‐Smith et al, 2009; Inukai et al, 2012; Jain et al, 2016; Khogeer et al, 2019; Ma et al, 2012) of all T‐ALL cases, possibly attributed to the different ages and other demographic and geographical demographic profiles of the patients included in these studies. The findings of our study reported the prevalence of ETP‐ALL to be higher in adults as compared to children, a conclusion in line with existing literature, thus corroborating this finding.…”

“…We compared the previously described flow cytometry‐based scoring systems; a five‐ marker based scoring proposed by Chandra et al (2021), designated as M5, six‐marker based scoring presented by Inukai et al (2012) defined as M6 to assess the utility of these scoring systems for distinguishing ETP‐ALL from non‐ETP‐ALL in our study population. Further, we modified two of the previously described scoring systems, M6 and an 11‐marker‐based panel designated as M11 in this study proposed by Inukai et al and assigned these modified panels as M6(1a) and M7 (Tables 1–4) and compared them with M5 and M6 scoring systems and assessed their utility in distinguishing ETP from non‐ETP‐ALL.…”

“…Many different scoring systems have been proposed based on the immunophenotypic patterns of flowcytometry for the accurate diagnosis of ETP‐ALL. These are based on five, six, or eleven markers with varying sensitivity and specificity (Chandra et al, 2021; Inukai et al, 2012). However, the challenge persists regarding which scoring system is to be adopted in practice.…”

Prognostic Significance of Comprehensive Gene Mutations and Clinical Characteristics in Adult T-Cell Acute Lymphoblastic Leukemia Based on Next-Generation Sequencing

“…The incidence of ETP-ALL gradually increased with age, which was 5.5%–13% in children ( 54 , 55 ) and 30%–50% in adults ( 56 – 58 ). The incidence of adult ETP-ALL in our data was 46.7%.…”