Background: Conventional criteria for ganglioneuroblastoma (GNB) do not require the presence of ganglioneuromatous component for pathologic diagnosis. This leads to inclusion of a mixed variety of neuroblastic tumors in the category of GNB. Therefore, GNB diagnosed by conventional criteria includes tumors showing more than 5% ganglion cells but no predominant ganglioneuromatous component, as well as tumors containing predominant ganglioneuromatous component. By previously described modified criteria, the former would be considered differentiating neuroblastoma (NB), and only the latter would be considered GNB. Data on Pediatric Oncology Group cases were analyzed to compare the prognostic subgroups of GNB diagnosed by conventional and modified criteria. The two prognostic subgroups (low risk and high risk) were defined on the basis of previously described prognostic differences between histologic grades of differentiating NBs and subtypes of GNB.
Methods: Pathologic data from cases of neuroblastic tumors registered on Pediatric Oncology Group NB protocols 8104 and 8441 were reviewed. The GNBs diagnosed by conventional and modified criteria were divided into low-risk and high-risk histology subgroups as follows: (1) GNB by conventional criteria: low-risk group, differentiating NB of histologic grades 1 and 2 and GNB of intermixed and borderline subtypes; high-risk group, differentiating NB of histologic grade 3 and GNB of nodular subtype; (2) GNB by modified criteria: low-risk group, GNB of intermixed and borderline subtypes; high-risk group, GNB of nodular subtype.
Results: The low- and high-risk subgroups of GNBs diagnosed by conventional (69 cases) and modified (36 cases) criteria showed statistically significant differences in survival (P = .03 and .01, respectively). However, from the histologic point of view, GNBs diagnosed by modified criteria form a more uniform morphologic group, which can be divided into low- and high-risk subgroups by a single set of morphologic criteria. In contrast, GNBs diagnosed by conventional criteria form a heterogeneous group, which requires two sets of criteria (ie, histologic grade and subtypes of GNB) for its classification into low- and high-risk subgroups.
Conclusions: The modified criteria for GNB define a morphologically uniform group of neuroblastic tumors to which a single set of prognostic criteria can be applied. It is recommended that the term GNB should be used both clinically and pathologically to designate a distinctive subgroup of neuroblastic tumors, in contrast to the current use, which designates both NB and GNB.