Single copies of the N-myc oncogene in neuroblastomas from children presenting with the syndrome of opsoclonus-myoclonus.

Patients with neuroblastoma who present with the syndrome of opsoclonus and myoclonus enjoy a remarkably good prognosis independent of their stage of disease or their age at diagnosis. The presence of N-myc amplification also has been found to be an independent prognostic factor in neuroblastoma. Patients with multicopy N-myc tumors have rapid tumor progression whereas those with single-copy tumors have a significantly better progression-free survival. The authors examined four primary, untreated neuroblastomas for the N-myc copy number from patients who presented with opsoclonus and myoclonus. All four tumors had single copies of N-myc, and all four patients are alive with no evidence of recurrent disease with 6+ to 54+ months' follow-up. This appears to be the only report of N-myc analysis in this group of children. It would be interesting to analyze more neuroblastomas from patients who present with opsoclonus and myoclonus to determine how many of these patients have single N-myc copy tumors.