Histopathology defines prognostic subsets of ganglioneuroblastoma, nodular

Ganglioneuroblastoma, nodular (GNBn) is a rare subtype of the family of neuroblastic tumors (neuroblastoma, ganglioneuroblastoma, and ganglioneuroma) that are classified in the unfavorable histology group according to the International Neuroblastoma Pathology Classification (Shimada system). Tumors of this subtype have been considered to represent a prototypic example of biologically and clinically nonaggressive (Schwannian stroma-rich and stroma-dominant) components combined with biologically and clinically aggressive nodular (Schwannian stroma-poor) components. However, detailed histopathologic analysis as well as thorough prognostic evaluation of patients with this subtype has not been reported.

Pathology slides and reports from a total of 70 GNBn patients from the Children's Cancer Group (CCG)-3881 and CCG-3891 studies were reviewed. Sixty-eight tumors were classified in the favorable subset (FS) or the unfavorable subset (US) based on the evaluation of nodular components by applying the same histopathologic criteria (patient age, grade of neuroblastic differentiation, mitosis-karyorrhexis index) that are used for neuroblastomas in the International Neuroblastoma Pathology Classification. Patient prognosis as well as clinical and biologic characteristics within the subsets were analyzed, and the results were compared with those from 654 non-GNBn patients who were enrolled in the same CCG studies during the same period.

Patients with GNBn tumors, usually diagnosed at age > 1 year, had a significantly lower overall 5-year event free survival (EFS) rate than patients with non-GNBn subtypes (44.7% EFS vs. 65.0% EFS; P = 0. 0073). A significant difference in the outcome of the patients between the FS (22 patients; 86.1% EFS; 95.0% survival rate) and the US (46 patients; 29.0% EFS; 40.7% survival rate) of the GNBn subtype (P < 0.0005) was shown. When the cohort of patients with GNBn tumors was subdivided into FS and US, the outcomes were similar to those of patients with tumors of favorable histology (397 patients; 90.5% EFS; 97.6% survival rate) and with tumors of unfavorable histology (257 patients; 27.0% EFS; 35.7% survival rate) of the non-GNBn type. The patients with US tumors frequently (63.0%) presented with distant metastasis.

The current study demonstrates that the nodular components in GNBn tumors are not always aggressive. The prognosis of these patients can be determined by the analysis of age-linked histopathologic features.