Insulinomas account for 50% of all islet-cell tumors and are the most common islet-cell tumor subtype.
The typical appearance of a pancreatic islet-cell tumor is a well-circumscribed, solitary, hypervascular mass (Figure 4).
Once the diagnosis and staging of a pancreatic islet-cell tumor is performed, imaging is helpful in determining the success of surgical treatment and monitoring for signs of recurrence.
Although pancreatic islet-cell tumors account for only 1% to 5% of all pancreatic neoplasms, they represent an important subset of pancreatic neoplasms due to their substantially improved prognosis compared to pancreatic adenocarcinoma.
Ninety-five percent of pancreatic islet-cell tumors are solitary and sporadic.
On the other hand, hyperfunctioning islet-cell tumors (referred to as syndromic islet-cell tumors) manifest much earlier, and at a much smaller size due to symptoms caused by hormonal oversecretion.
Pancreatic islet-cell tumors other than insulinomas have a higher malignancy rate, approaching 60% to 90%.
Unlike sporadic islet-cell tumors, inherited pancreatic islet-cell tumors are usually multiple in location and most often related to MEN-1.
Pancreatic islet-cell tumors spread first to regional lymph nodes, then to the liver, bone, and rarely, to distant sites such as the lung or brain.
(11) Recent literature suggests that MRI may be at least as sensitive as multiphasic CT in detecting pancreatic islet-cell tumors. (12) In our experience, a multimodality approach is useful for diagnosing and staging pancreatic islet-cell tumors as well as helping to guide surgery (Figures 2-6).
Typically, pancreatic islet-cell tumors and metastases are best seen during the late arterial phase (Figures 4, 9).
On ultrasound, pancreatic islet-cell tumors are generally hypoechoic and well circumscribed.