Neuroblastoma. Neuroblastoma is the most common nonhematologic extracranial tumor of childhood and is the most frequent abdominal malignant mass lesion except for Wilm’s tumor between ages 1-4 years. Treatment by combined radiation and chemotherapy produces excellent results in sufficient patients that diagnosis has become of more than academic interest. It usually presents as an abdominal mass, and frequently the only method of definitive diagnosis is abdominal exploration with biopsy. Urine vanillylmandelic acid (VMA) levels have been found elevated in more than 90% of patients (literature range, 61%–100%), although some elevations were not present on initial specimens. Homovanillic acid (HVA), a metabolic product of the catecholamine precursor dopamine, has been reported to be abnormal in about 80% (53%–93%) of patients. Combined VMA and HVA positive results include nearly 100% of patients. Bone marrow aspiration has been reported abnormal in up to 50% of patients. Therefore, some investigators recommend that bone marrow aspiration be done on all patients, since the finding of marrow metastases rules out surgery alone as a curative procedure.

Neuroblastoma discovered during the first year of childhood has a much better prognosis than cases found afterward. DNA analysis by FCM has shown that aneuploid neuroblastomas have in general a better response to chemotherapy and a better prognosis than diploid ones, the opposite of usual circumstances. In addition, 30%–40% of patients have detectable n-myc oncogene (located on chromosome 2), and in those patients in whom the n-myc molecule is amplified (increased in number) over 3 times, there is a worse prognosis. There is also a very high incidence of other chromosome abnormalities, such as deletion of chromosome 1, but this has less prognostic value. Other prognostic tests include serum ferritin, where normal values (less than 150 ng/ml, but reference range is age related) are associated with early stage and less aggressive tumors. Ferritin can also be used to monitor the effect of chemotherapy. Serum neuron-specific enolase has also been reported to have prognostic value, with levels over 100 ng/ml being associated with poor prognosis; but the enzyme cannot be used to monitor therapy.