INS and Hypoglycemia: Post-operative persistence of F-PNEN-derived endocrine syndromes was reported in three cases of PD (15.8%), all due to the persistence of hypergastrinemia and positivity of the secretin stimulation test, caused by residual gastrin-secretin lesions, and in two cases of DP (10.5%), one being persistent hypergastrinism and one being hypoglycemia from an insulin-secreting lesion.