Pancreatic and duodenal neuroendocrine tumors producing somatostatin

Background Somatostatin-producing NETs (SOM-NETs) of the duodenum (d) and pancreas (p) are rare. In pathological series, SOM-positive dNETs may be 26% and pNETs 4%; some of them associated to inherited genetic syndromes. Methods We retrieved the clinical and pathological records of 432 cases of d- and p-NETs operated on in our Centre from 1988 to 2022. Eleven patients (5 F/6 M) had predominant or exclusive staining of somatostatin and were defined SOM-NETs. Last follow up was in November 2023. Results There were 8/45 d-NETs (18%) and 3/393 p-NETs (0.8%). Two cases of d-NET occurred in NF-1 patients and one p-NET had a MEN-1. Regarding dNETs: mean size was 1.8 cm (range 0.75-4.5), six were located at the papilla, grade was available in 7 cases (five G1, two G2), 4 had lymph-node metastases and one liver metastases. Two patients had a surgical ampullectomy, 5 pancreatoduodenectomy (PD), one gastric/biliary bypass (liver metastases). Regarding pNETs: tumor size from 3.0 to 4.5 cm, two located in the head (enucleation, and PD), one in the body-tail (distal pancreatectomy), one had lymph-node metastasis, one had a pancreatic recurrence (MEN-1) after 10 years. Three late unrelated deaths occurred in patients 79 to 120 months after PD. The other patients are alive from one to 16 years after surgery. Conclusions SOM-NETs (2.5% in our series) are rare in the duodenum and even more in the pancreas. Nodal metastases are frequent, but liver secondaries occasionally occur. Long term-survival without recurrence after resection is the common behavior.