The diagnosis of neuroblastoma requires the involvement of pathologists who are familiar with childhood tumors. Some neuroblastomas cannot be differentiated, via conventional light microscopy, from other small round blue cell tumors of childhood, such as lymphomas, primitive neuroectodermal tumors, and rhabdomyosarcomas.
The minimum criterion for a diagnosis of neuroblastoma, as established by international agreement, is that diagnosis must be based on one of the following:
- An unequivocal pathologic diagnosis made from tumor tissue by light microscopy (with or without immunohistology, electron microscopy, or increased levels of serum catecholamines [dopamine and norepinephrine] or urinary catecholamine metabolites [VMA or HVA]).
- The combination of bone marrow aspirate or trephine biopsy containing unequivocal tumor cells (e.g., syncytia or immunocytologically-positive clumps of cells) and increased levels of serum catecholamines or urinary catecholamine metabolites.
Between 1975 and 2002, the 5-year survival rate for neuroblastoma in the United States has remained stable at approximately 87% for children younger than 1 year and has increased from 37% to 65% in children aged 1 to 14 years. The 5-year overall survival for all infants and children with neuroblastoma has increased from 46% when diagnosed between 1974 and 1989, to 71% when diagnosed between 1999 and 2005; however, this single number can be misleading because of the extremely heterogeneous prognosis based on the neuroblastoma patient's age, stage, and biology. (Refer to the Cellular Classification of Neuroblastic Tumors section of this summary for more information.) Approximately 70% of patients with neuroblastoma have metastatic disease at diagnosis.
The prognosis for patients with neuroblastoma is related to the following:[48,49,50,51]
- Age at diagnosis.
- Clinical stage of disease.
- Site of the primary tumor.
- Tumor histology.
- Regional lymph node involvement (in children older than 1 year, but this is controversial).
- Response to treatment.
- Biological features.
Some of these prognostic factors have been combined to create risk groups to help define treatment. (Refer to the International Neuroblastoma Risk Group Staging System section and the Children's Oncology Group Neuroblastoma Risk Grouping section of this summary for more information.)