Bilateral bone marrow aspirates and biopsies should be performed to exclude metastatic disease.
Biopsy or resection of the primary tumor (stage I or II disease) is performed to collect tissue samples for biologic studies used to assign the patient into the appropriate risk category. Most centers in the United States perform limited open biopsies when the primary tumor is unresectable upfront. Adequate tissue is needed to perform molecular studies that aid in risk assignment. Extensive resections should be avoided upfront if they may place patient at excessive risk from morbidity or mortality from surgery. Neuroblastoma is a chemo-sensitive tumor; thus, second-look surgery to resect a residual primary may be a safer procedure with biopsy only performed upfront.
Tissue samples from a primary or metastatic tumor may be undifferentiated and confused with other small, round, blue cell tumors of childhood; however, immunohistochemical stains can aid with tissue diagnosis.
Molecular techniques, such as fluorescent in situ hybridization (FISH), can detect MYCN amplification, an important prognostic marker. Polymerase chain reaction (PCR) can identify specific translocations, such as t(11;22), in Ewing sarcoma and t(2;13) in alveolar rhabdomyosarcoma, thus ruling out neuroblastoma.
Neuroblastoma in bone marrow can be difficult to distinguish from other small, round, blue cell tumors of childhood.
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Histologic subtypes of neuroblastoma. Top right panel, neuroblastoma: A monotonous population of hyperchromatic cells with scant cytoplasm. Bottom left panel, ganglioneuroblastoma: Increased schwannian stroma. Bottom right panel, ganglioneuroma: Mature ganglion cell with schwannian stroma.
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CT scan of abdomen in a patient with a retroperitoneal mass arising from the upper pole of the left kidney and elevated urine catecholamines.
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MRI of a left adrenal mass. The mass was revealed by fetal ultrasonography at 30 weeks' gestation. During infancy, the mass was found on the inferior pole of the left adrenal and was completely resected. Before surgery, the metastatic workup was negative. Surgical pathology service confirmed a diagnosis of neuroblastoma. After 3 years of follow-up care, no recurrence was observed.
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A one-week-old neonate had abdominal ultrasonography for evaluation of projectile vomiting. A right adrenal mass (100% cystic) was an incidental finding. Evaluation of the mass by CT was consistent with an adrenal bleed (3.6 x 3.1 x 2.4 cc). The infant was followed at 2 weeks (2-dimensional size diminished to 1.5 x. 2.4 cm2 on ultrasonography) and then at 6 weeks to document that the adrenal bleed continued to involute. Urine catecholamines were normal.
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Table. A Consensus Pretreatment Classification schema by the International Neuroblastoma Risk Group (INRG). This schema is based in the INRG stage, age, histologic category, tumor grade of differentiation, MYCN sastus, 11q-aberrations and DNA ploidy. A combination of these characteristics results in four risk groups noted in the last column: very low, low, intermediate and high risk, with the following 5 year EFS: >85%, >75%-85%, >50%-75%, and < 50%. These risk groups are distributed among the different stages and labeled alphabetically from A to R (without letters L and M to avoid confusion with the INRG stage notation). Notations in the table are as follow: L1, localized tumor confined to one body compartment; L2, locoregional tumor with presence of one or more risk factors defined radiologically; M, distant metastatic disease (except stage MS); MS, metastatic disease confined to skin, liver and/or bone marrow in children < 18 months of age. GN, ganglioneuroma; GNB, ganglioneuroblastoma; Amp, amplified; n/amp, not amplified. (Adapted from The International Neuroblastoma Risk Group (INRG) Classifications System: An INRG Task Force Report by Cohn, et al. Journal of Clinical Oncology 27(2):289-297, 2009).
