Pediatric Precursor B-Cell Lymphoblastic Malignancies: From Extramedullary to Medullary Involvement

Abstract

B-cell lymphoblastic lymphoma (BCP-LBL) and B-cell acute lymphoblastic leukemia (BCP-ALL) are the malignant counterparts of immature B-cells. BCP-ALL is the most common hematological malignancy in childhood, while BCP-LBL accounts for only 1% of all hematological malignancies in children. Therefore, BCP-ALL has been well studied and treatment protocols have changed over the last decades, whereas treatment for BCP-LBL has stayed roughly the same. Clinical characteristics of 364 pediatric patients with precursor B-cell malignancies were studied, consisting of BCP-LBL (n = 210) and BCP-ALL (n = 154) patients. Our results indicate that based on the clinical presentation of disease, B-cell malignancies probably represent a spectrum ranging from complete isolated medullary disease to apparent complete extramedullary disease. Hepatosplenomegaly and peripheral blood involvement are the most important discriminators, as both seen in 80% and 95% of the BCP-ALL patients and in 2% of the BCP-LBL patients, respectively. In addition, we show that the overall survival rates in this cohort differ significantly between BCP-LBL and BCP-ALL patients aged 1–18 years (p = 0.0080), and that the outcome for infants (0–1 years) with BCP-LBL is significantly decreased compared to BCP-LBL patients of all other pediatric ages (p < 0.0001).

Precursor B-cell Lymphoblastic Lymphoma in Children: Hacettepe Experience

“…In a recent multicentric study, Kroeze and colleagues compared the clinical characteristics of PBLL and B-ALL. Most of the PBLL patients were diagnosed with advanced disease stage as in our study, and extramedullary localizations were more common 13 …”

“…Most of the PBLL patients were diagnosed with advanced disease stage as in our study, and extramedullary localizations were more common. 13 In both PTLL and PBLL clinical and genetic and molecular characteristics to be used for prognostic stratification are lacking due to small patient numbers. Patients are stratified based on stage alone in most treatment protocols as limited-stage disease and advanced-stage disease.…”

How I approach B‐lymphoblastic lymphoma in children

“…B‐lymphoblastic lymphoma (B‐LLy) is a rare non‐Hodgkin lymphoma (NHL) with a paucity of established features for predicting therapy response. Its clinical characteristics suggest that B‐LLy and B‐lymphoblastic leukemia (B‐ALL) are related diseases on a continuum between completely isolated medullary disease to exclusive extramedullary involvement 1 . However, several features suggest unique biology in B‐LLy, 2 namely, its more indolent presentation involving primarily lymphatic and extranodal sites 3,4 …”

“…Its clinical characteristics suggest that B-LLy and B-lymphoblastic leukemia (B-ALL) are related diseases on a continuum between completely isolated medullary disease to exclusive extramedullary involvement. 1 However, several features suggest unique biology in B-LLy, 2 namely, its more indolent presentation involving primarily lymphatic and extranodal sites. 3,4 Historically, patients with T-and B-LLy were treated together, regardless of phenotype.…”

18F‐FDG‐PET/CT imaging in diagnostic workup of pediatric precursor B‐cell lymphoblastic lymphoma

“…B‐cell precursor lymphoblastic lymphoma (BCP‐LBL) is predominantly characterized by extramedullary disease, including involvement of the peripheral lymph nodes, soft tissue, skin, and bone 1 . Patients with BCP‐LBL are currently treated according to stage‐based protocols (Murphy staging and Revised International Pediatric Non‐Hodgkin Lymphoma Staging System [IPNHLSS]), 2,3 including the commonly used EICNHL EURO‐LB02 protocol, 4 as well as its successor the LBL2018 protocol (NCT04043494).…”