Can Pancreatic Neuroendocrine Tumour Biopsy Accurately Determine Pathological Characteristics?

Background: Assessment of the pathological characteristics of pancreatic neuroendocrine tumours is crucial for appropriate management. We compared preoperative pathological data with surgical specimens for accuracy.

Methods: Surgical patients with pancreatic neuroendocrine tumours who underwent preoperative endoscopic ultrasound-guided fine needle aspiration of the primary tumour or biopsy of liver metastasis were retrospectively included. Tumour differentiation and the Ki67 proliferation index on biopsies were compared with pancreatic specimens.

Results: Fifty-seven patients were included. A preoperative biopsy of the primary tumour or of a liver metastasis was obtained in 48 and 9 patients respectively. Tumour differentiation was high in 98%, and poor in 2% on biopsy and high in 100% of surgical specimens. Ki67 index values were 0 (0-19) and 2 (0-15) on biopsy and surgical specimens (p=0.01). Correlation between preoperative and surgical findings was stronger for liver (r=0.62, p=0.001) than for pancreas (r=0.23, p=0.11). Correlation for pancreas varied according to the tumour pattern: solid (r=0.24, p=0.16), mixed (r=0.91, p=0.0036) or cystic (r=0.04, p=0.89). Tumour grade was different between pancreatic biopsies and surgical specimens, for grade 1 (63% vs 37%) and grade 2 (28% vs 72%), p=0.0007.

Conclusions: Tumour grade assessment is accurate in biopsies of liver metastases of pancreatic neuroendocrine tumours, while pancreatic fine-needle aspiration biopsies are less accurate.