Diagnosis of Pancreatic Neuroendocrine Tumors

Abstract

Pancreatic neuroendocrine tumors (PNETs) are relatively rare; however, the incidence has increased over the last few decades. They are classified as functional or non-functional tumors according to the presence of associated clinical symptoms. The majority are non-functional tumors. For classification and staging, the World Health Organization 2010 classification system is the most commonly accepted. Chromogranin A is the most sensitive marker but has insufficient specificity. In general, PNETs are hypervascular tumors, and multiphasic contrast-enhanced computed tomography is considered the first choice for imaging study. Multiphasic magnetic resonance imaging can detect PNETs smaller than 2 cm and small liver metastasis compared with other modalities. Somatostatin receptor scintigraphy is often used in cases where functional PNETs are suspected. Positron emission tomography (PET) scan with 18F-fluorodeoxyglucose cannot visualize PNETs, but PET with 68-Ga DOTATATE can. Endoscopic ultrasonography can characterize smaller PNETs using contrast and confirm histology through fine needle aspiration or biopsy. In this article, we review the characteristics of grading systems and diagnostic modalities commonly used for PNETs.

Malignant Insulinoma with Multiple Liver Metastases and Hypercalcitoninemia in a Patient with Type 2 Diabetes Mellitus Presenting as Recurrent Episodes of Diaphoresis due to Severe Hypoglycemia

“…eir incidence is around 1 case per 100,000 people, and only about 10% of them are classified as functional, as they release hormones or peptides that cause specific symptoms and signs [2]. With an estimated incidence of 4 cases per 1 million person-years [3], insulinomas and insulin-producing tumors, are the most common functional PNETs, and unlike other PNETs, which are malignant in 50-100% of cases, they are malignant only in about 10% of cases [4].…”

Diagnostic Performance of Endoscopic Ultrasound (EUS)/ Endoscopic Ultrasound – Fine Needle Aspiration (EUS-FNA) Cytology in Solid and Cystic Pancreatic Neuroendocrine Tumours

“…Surgical and autopsy series suggest that pNETs can account for 0.8% to 10% of all pancreatic neoplasms [17]. Pancreatic NETs can occur sporadically or associated with inherited syndromes such as multiple endocrine neoplasia (MEN 1), Von Hippel Lindau disease, Von Recklinghausen disease and tuberosclerosis [18].…”

EUS in Pancreatic Cysts

“…Cystic neuroendocrine tumors account for only 8-17 % of pancreatic neuroendocrine tumors and are usually nonfunctional [34]. Acinar cystadenocarcinoma is extremely rare with fewer than 10 cases reported in literature and typically presents with abdominal pain and a multilocular cystic lesion [35].…”

“…Cystic neuroendocrine tumors are highly vascularized with early enhancement of the rim during early arterial imaging with MRI ( Fig. 31.11) [34].…”