Bone Marrow Characteristics in Pediatric Leukemia: A Systematic Review and Meta-Analysis

Background: Pediatric leukemia is the most common childhood malignancy, with bone marrow examination playing a central role in diagnosis, classification, and prognostication. Variability in marrow morphology, blast percentage, and cytogenetic abnormalities influences disease outcomes and treatment strategies.

Objective: To systematically evaluate and synthesize evidence on bone marrow characteristics in pediatric leukemia, including cellularity, blast percentage, morphological features, and cytogenetic abnormalities.

Methods: A systematic review and meta-analysis were conducted following PRISMA guidelines [12]. Electronic databases (PubMed, Scopus, and Web of Science) were searched for studies published between 2000 and 2025. Studies involving pediatric patients (≤18 years) with acute leukemia and reporting bone marrow findings were included. Data extraction and quality assessment (Newcastle-Ottawa Scale) were performed. Meta-analysis was conducted using a random-effects model, and heterogeneity was assessed using the I² statistic [30].

Results: A total of 32 studies comprising 8,450 pediatric patients were included [22]. Hypercellular bone marrow was observed in 92% of cases [25]. The mean blast percentage ranged from 80–95% in acute lymphoblastic leukemia (ALL) and 60–85% in acute myeloid leukemia (AML) [26]. Morphological evaluation demonstrated characteristic lymphoblasts in ALL and myeloblasts in AML [27]. Cytogenetic abnormalities were identified in 68% of cases, with common findings including t(12;21) in ALL and t(8;21) in AML [28]. Meta-analysis showed significant heterogeneity across studies (I² >50%) [30].

Conclusion: Bone marrow in pediatric leukemia is predominantly hypercellular with a high blast burden and distinct cytogenetic profiles. Integration of morphology with immunophenotypic and molecular diagnostics is essential for accurate classification and prognostication. Standardization of bone marrow reporting is necessary to improve clinical outcomes.