Shimada et al developed a histopathologic classification in patients with neuroblastoma. [3] This classification system was retrospectively evaluated and correlated with outcome in 295 patients with neuroblastoma who were treated by the Children's Cancer Group (CCG). Important features of the classification include (1) the degree of neuroblast differentiation, (2) the presence or absence of Schwannian stromal development (stroma-rich, stroma-poor), (3) the index of cellular proliferation (known as mitosis-karyorrhexis index [MKI]), (4) nodular pattern, and (5) age. Using these components, patients can be classified into the following histology groups:
Favorable histology group includes the following:
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Patients of any age with stroma-rich tumors without a nodular pattern
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Patients younger than 18 months with stroma-poor tumors, an MKI of less than 200/5000 (200 karyorrhectic cells per 5000 cells scanned), and differentiated or undifferentiated neuroblasts
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Patients younger than 60 months with stroma-poor tumors, an MKI of less than 100/5000, and well-differentiated tumor cells
Unfavorable histology group includes the following:
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Patients of any age with stroma-rich tumors and a nodular pattern
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Patients of any age with stroma-poor tumors, undifferentiated or differentiated neuroblasts, and an MKI more than 200/5000
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Patients older than 18 months with stroma-poor tumors, undifferentiated neuroblasts, and an MKI more than 100/5000
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Patients older than 18 months with stroma-poor tumors, differentiated neuroblasts, and an MKI of 100-200/5000
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Patients older than 60 months stroma-poor, differentiated neuroblasts, and an MKI less than 100
Shimada et al’s original classification was adopted and integrated into the International Neuroblastoma Pathology Classification (INPC). This was most recently revised. [4] The INPC system remains age-dependent.
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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).
