Serotonin-Secreting Neuroendocrine Tumours of the Pancreas

Abstract

Background: Serotonin-secreting pancreatic neuroendocrine tumours (5-HT-secreting pNETs) are very rare, and characterised by high urinary 5-hydroxyindole-acetic acid (5-HIAA) levels (or high serum 5-HT levels).

Methods: Patients with 5-HT-secreting pancreatic neoplasms observed in our unit (1986-2015) were included. Diagnosis was based on urinary 5-HIAA or serum 5-HT levels.

Results: Seven patients were enrolled (4 M/3 F), with a median age of 64 (range 38-69) years. Two patients had a carcinoid syndrome. Serum 5-HT was elevated in four patients. Urinary 5-HIAA levels were positive in six patients. The median tumour size was 4.0 (range 2.5-10) cm. All patients showed liver metastases at diagnosis. None underwent resective surgery; lymph node/liver biopsies were taken. Six lesions were well-differentiated tumours and one a poorly differentiated carcinoma (Ki67 range 3.4-70%). All but one patient received chemotherapy. Four patients received somatostatin analogues; three patients underwent ablation of liver metastases. One patient is alive with disease 117 months after observation. All the others died from disease progression after a follow-up within 158 months.

Conclusions: Primary 5-HT-secreting pNETs are mostly metastatic to the liver; patients are not amenable to resective surgery. Despite high 5-HIAA urinary levels, few patients present with carcinoid syndrome. A five-year survival rate of 42.9% may be achieved with multimodal treatment.

Keywords: pancreatic neuroendocrine neoplasm; primary pancreatic carcinoid; serotonin-producing pancreatic tumour; serotonin-secreting pancreatic tumour.

Figure 1

Angiography of the celiac trunk showing a mass in the pancreatic head (big arrow) and multiple liver metastases (small arrow) in a patient with carcinoid syndrome (case n.1).

Figure 2

Computed tomography scan 2 (a) and ¹⁸F-FDG positron emission tomography/CT 2 (b) showing a pancreatic neuroendocrine tumor in the body of the pancreas (white arrow) with multiple liver metastases (case n.7).

Figure 3

Abdominal magnetic resonance imaging showing several huge mesenteric and left gastric vein compensation collateral circles due to portal vein thrombosis and portal hypertension (case n.6).

Figure 4

Representative hematoxylin and eosin stain 4 (a) and serotonin immunostaining 4 (b) of case n.7. The neoplasia was characterized by a trabecular pattern of growth, high mitotic activity (MIB1-labelling index > 70%), areas of necrosis, and high-grade cytonuclear pleomorphism. A final diagnosis of G3 neuroendocrine tumour (NET G3) was reached. The lesion showed a heterogeneous serotonin pattern of staining, which was positive in most neoplastic cells (original magnifications, 20×).