Somatostatinoma: Beyond neurofibromatosis type 1 (Review)

Abstract

Somatostatinoma is a tumour mainly originating from pancreas or duodenum; overall with an incidence of 1/40 million persons. We introduce a narrative review of literature of somatostatinoma including the relationship with neurofibromatosis type 1. Clinical presentation includes: Diabetes mellitus, cholelithiasis, steatorrhea, abdominal pain, and obstructive jaundice while papillary tumour may cause acute pancreatitis. The neoplasia may develop completely asymptomatic or it is detected as an incidental finding during an imaging or a surgical procedure. It may be sporadic or associated to genetic backgrounds especially for duodenal localisation as neurofibromatosis type 1 (NF1 gene with malfunction of RAS/MAPK pathway) or Pacak-Zhuang syndrome (EPAS1 gene encoding HIF). Surgery represents the central approach if feasible but the prognostic depends on location, and grading as indicated by WHO 2017 classification of neuroendocrine tumours. Previously known as Von Recklinghausen disease, neurofibromatosis type 1, the most frequent neurocutaneous syndrome, is an autosomal dominant disorder including: Café-au-lait spot, skin fold freckling on flexural zones, and neurofibromas as well as tumours such as gliomas of optic nerve, gastrointestinal stromal tumours (GISTs), iris hamartomas and brain tumours. Duodenal somatostatinoma is associated with the syndrome which actually involves more often a duodenal tumour of GIST type than a somatostatin secreting neoplasia. Other neuroendocrine tumours are reported: Gastrointestinal NENs at the level of rectum or jejunum and pheocromocytoma. Overall, one quarter of subjects have gastrointestinal tumours of different types. Somatostatinoma, when not located on pancreas but in duodenoum, may be registered in subjects with neurofibromatosis type 1 most probably in addition to other tumours. Overall, this type of neuroendocrine tumour with a challenging presentation has a poor prognosis unless adequate radical surgery is promptly offered to the patient.