Abstract
Acute lymphoblastic leukemia (ALL) is the most common pediatric malignancy, yet its presentation in infants under one year is rare and often atypical. This report describes a four-month-old female infant who presented with fever, vomiting, and pallor, ultimately diagnosed with precursor B-cell ALL. Laboratory investigations revealed severe anemia, thrombocytopenia, and hyperleukocytosis, with 95% circulating blasts. Immunophenotyping confirmed the diagnosis, and further cytogenetic studies were recommended. This report emphasizes the need for early recognition of clinical and laboratory signs, such as hyperleukocytosis, severe anemia, and a high burden of circulating blasts in infants, to facilitate timely diagnosis and initiation of risk-adapted treatment strategies for ALL.