Background Ganglioneuroblastoma intermixed (GNBi) and ganglioneuroma (GN) are benign subtypes of neuroblastic tumors. Primary observation has become accepted management for some patients with surgical operative strategies evolving to be less aggressive. Objectives Our study examines evolving management in a UK cohort investigating natural history, biology and clinical features of GN and ganglioneuroblastoma-intermixed (GNBi) in those having observation or surgery. Methods Retrospective review of histologically confirmed GN and GNBi managed over a 30 year period. Clinical, pathological features, tumor dimensions, management and outcomes are all recorded. Results A total of 259 patients were identified (GN= 163, GNBi = 93, median age = 62 months). 201(78%) had upfront surgery and 58 (22%) were actively observed. Of the 58 observed - 21 (36%) later required surgery due to progressive tumour growth (52%). Gross total resection was achieved in 79% of patients with a 19% complication rate. Presence of image defined risk factors and large tumour size correlated with incomplete resection (p < 0.05 in both). Forty-five index cases (39%) had change in pathology between biopsy and surgery with 14 patients (12%) altered from ‘favourable‘ to ‘unfavourable’. Conclusion Our findings show surveillance alone may be considered a safe approach. However, a significant number of index patients may eventually require operative surgery with development of symptoms. Extent of surgical resection did not impact overall survival (OS); however it improved symptom(s) resolution.

BACKGROUND Preoperative evaluation of Image Defined Risk Factors (IDRFs) in neuroblastoma (NB) is crucial for determining suitability for upfront resection or tumor biopsy. IDRFs are linked with a higher potential morbidity at operation and lessen the chance of complete tumor resection. The IDRFs do not all carry the same weight in predicting tumor complexity and surgical risk. In this study we aimed to assess and categorize the degrees of surgical complexity (Surgical Complexity Index, SCI) in NB resection.  PROCEDURE A panel of 15 surgeons was involved in an electronic Delphi consensus survey to identify and score a set of shared items predictive and/or indicative of surgical complexity, including the number of preoperative IDRFs. Risk categories included - (a) Standard risk; (b) Moderate risk; (c) High risk; (d) Very high risk. A shared agreement included the achievement of at least 75% consensus focused on a single category or, alternatively, on the sum between the prevailing category and an immediately closest one. RESULTS After 3 Delphi rounds, agreement was established on 25/27 items (92.6%). A severity score was established for each item ranging from 0 to 3 with an overall SCI range varying from a minimum score of zero to a maximum score of 29 points for any given patient.  CONCLUSIONS A consensus on a SCI to stratify the risks related to tumor resection was established by the panel experts. This index will now be deployed to critically assign a better severity score to IDRFs involved in NB surgery.