Classical and atypical neuroblastoma--case reports

Neuroblastoma is the most common extracranial solid tumor in early childhood with a pluripotent neural cell origin. The disease often infiltrates the bone marrow, and these cases are candidates for flow cytometric diagnosis and disease follow-up, more so in atypical cases that are diagnostically challenging by other methods. Here, we report two neuroblastoma cases, one with characteristic neuroblastoma cells forming Homer-Wright rosettes found in the bone marrow sample by histological examination. This case showed the classical immunophenotype with CD81/CD56/CD117 positive and CD45 negative labeling and 80% bone marrow infiltration. Minimal residual disease measurement was performed in a regular fashion, and flow cytometry results showed good correlation with other disease markers. Analyzing 300,000 events provided a sensitivity level of 0.01%. The second case showed atypical cell morphology on histological examination, after which flow cytometric analysis was initiated. Atypical cells displayed CD81 and bright CD56 but CD117 negative immunophenotype, with a 28% bone marrow infiltration. In most cases the primary tumor can be identified, but in this particular case only bone marrow involvement could be detected using flow cytometry, as such making it a powerful tool for diagnosis and disease monitoring.