Composite gangliocytoma/neuroma and neuroendocrine tumour: a contemporary analysis of 71 cases shows risk factors for metastasis

Aims: To describe the clinicopathological features of composite gangliocytoma/neuroma and neuroendocrine tumour (CoGNET) and possible risk factors for nodal metastasis. Methods and results: We compiled a cohort of 71 cases from 19 institutions. Mean patient age was 58 years. Thirty-eight (54%) patients were male. Most patients (65%) had symptoms, including abdominal pain (20%) and gastrointestinal bleeding (19%). Most cases (70%) were described as a subepithelial mass/nodule, and nearly half (45%) were located in the 2nd portion of the duodenum. Mean tumour size was 2.2 cm, and most (87%) were well-circumscribed. Nearly all cases (96%) demonstrated all three histologic components, with the epithelioid component being the most predominant overall (mean 59%). All cases involved the submucosa, with 7 (10%) additionally involving the muscularis propria. Solid areas of ganglion-like cells were identified in 16/69 (23%) cases, glandular structure formation in 15/70 (21%), lymphovascular invasion (LVI) in 6/70 (9%) cases, and perineural invasion and necrosis in one case each. Nodal metastasis was identified at diagnosis in 8 (11%) cases; increased age, increased size, LVI and muscularis propria involvement were all significantly associated with nodal disease (P < 0.05). Follow-up data were available for 68 patients (mean 47 months); nearly all were alive without disease, though one patient developed liver metastasis after 8 months and died of the disease after 63 months. Conclusions: This largest series of CoGNET to date demonstrates that approximately 10% of cases develop nodal metastases. Large tumour size, muscularis propria involvement, advanced patient age and LVI appear to be risk factors for nodal metastasis.