Synchronous precursor B-cell acute lymphoblastic Leukemia and metastatic neuroblastoma in a child: a rare diagnostic challenge.

The synchronous occurrence of hematologic and solid malignancies in children is rare and poses diagnostic challenges. We report a 5-year-old boy with intermittent fever, hepatosplenomegaly, and a large abdominal mass. Initial laboratory investigations revealed severe anemia, and bone marrow flow cytometry demonstrated an abnormal blast population consistent with precursor B-cell acute lymphoblastic leukemia. Abdominal imaging revealed a heterogeneous right adrenal mass with internal calcifications suggestive of neuroblastoma. Due to the discrepancy between hematologic findings and radiologic features, a bone marrow biopsy showed small round blue cells with rosette-like structures. Immunohistochemistry, elevated neuron-specific enolase and urinary vanillylmandelic acid supported metastatic neuroblastoma. Bone scintigraphy demonstrated uptake in lumbar vertebrae. The patient was diagnosed with precursor B-cell acute lymphoblastic leukemia and stage IV metastatic neuroblastoma. This case highlights the importance of considering synchronous malignancies when clinical and radiologic findings are discordant, as early recognition is essential for accurate diagnosis and optimal management.