Revision of the International Neuroblastoma Pathology Classification: Confirmation of Favorable and Unfavorable Prognostic Subsets in Ganglioneuroblastoma, Nodular

Background: Ganglioneuroblastoma, nodular (GNBn) comprises one of the categories of peripheral neuroblastic tumors. All tumors in this category, according to the original International Neuroblastoma Pathology Classification, are classified into an unfavorable histology group. Subsequently, it has been reported that GNBn can be divided into two prognostic subsets, a favorable subset (FS) and an unfavorable subset (US).

Methods: Histology slides from 70 patients who were enrolled in Children's Cancer Group studies 3881 and 3891 and who had a diagnosis of GNBn were reviewed jointly by the members of International Neuroblastoma Pathology Committee (INPC): 1) to confirm the diagnosis of GNBn, 2) to identify the FS and US by applying the same age-linked criteria that were used to distinguish the favorable histology group and unfavorable histology group in conventional neuroblastoma tumors from the neuroblastomatous component of GNBn tumors, and 3) to verify the significant prognostic difference between these two subsets. The patients had been used in a previous study, and survival data for the patients were updated since the time of their last report.

Results: The review clarified and illustrated morphologic characteristics of classical GNBn and it variants. The diagnosis of GNBn was confirmed in 67 of 70 patients. There were 22 patients with GNBn in the FS and 45 patients with GNBn in the US. The estimated survival differences between the FS and US patients with GNBn were statistically significant (8-year event free survival rate: 86.1% vs. 32.2%; P = 0.0003; overall survival rate: 90.5% vs. 33.2%; P = 0.0003).

Conclusions: This study confirmed the recently defined prognostic subsets of GNBn. The INPC proposes to modify the International Neuroblastoma Pathology Classification by distinguishing the FS and the US among patients with GNBn tumors.