NEUROBLASTOMA PRESENTING AS ACUTE MONOBLASTIC LEUKEMIA

Purpose: We report a 5-year-old boy with stage 4 neuroblastoma initial ly diagnosed as having acute monoblastic leukemia (FAB M5A, AMoL), bas ed on bone marrow morphology, histochemistry, immunocytochemistry, imm unophenotyping, and cytogenetics, all consistent with AMoL. The patien t also had circulating blasts at diagnosis. After failing initial ther apy for AMoL and because of concerns about residual blasts with a clum ped appearance in the bone marrow, urinary homovanillic acid (HVA) and vanillylmandelic acid (VMA) and N-myc amplification in tumor cells we re evaluated and found to be positive, resulting in the diagnosis of n euroblastoma. Abdominal computerized tomography showed a left adrenal mass. A review of 10 reported cases of neuroblastoma with leukemic fea tures showed that seven of them were misdiagnosed as having leukemia, and in six of the seven, the diagnosis of neuroblastoma was made postm ortem. Conclusion: Neuroblastoma may be confused with acute leukemia, even with the use of modern techniques.