A Case Report of Insulinoma; Diagnosed in Phichit Hospital
Abstract
Insulinoma is functioning islet cell tumor (insulin-secreting tumor) of the pancreas. The patient usually has a set of clinical triad, Whipple’s triad, consists of 1) spontaneous hypoglycemia, followed by central nervous system and vasomotor symptoms, 2) low blood glucose level usually <50mg/dl, 3) relief of symptom by administration of glucose.4
Pancreatic insulinomas are uncommon tumor - the incidence being 1 per 250,000 people/year5 and are the most common endrocrine tumor of the pancreas. They are 80-90% single benign adenoma, 5-10% multiple adenoma/microadenomatosis (especially in MEN type I), 5-10% islet hyperplasia and 5-10% malignancy1. These benign tumors are a treatable cause of potential fatal hypoglycemia. About 60% of cases occur in women.4 Calcification is present in 20% of cases and may signify malignancy. The tumor occurs in all age groups - the peak incidence being between 40 to 60 years of age. The tumor size is usually small, having diameter of less than 2.5cm 9
They are demonstrated as round or oval, smoothly marginated solid homogeneously hypoechoic masses on sonographic examination, as hypoattenuation or isodensity or hyperattenuation on CECT (contrast enhanced computed tomography), as hypervascular lesion on angiography, and on MRI it is low signal intensity on fat-suppressed TIWI and hyperintense on T2WI + dynamic contrast-enhanced + suppressed inversion recovery images.1
The imaging modalities have been used for insulinoma investigations and detection rate are.8
- Trans abdominal ultrasound: readily available, inexpensive, noninvasive with detection rate of 25-65%
- Endoscopic ultrasound: equipment and expertise are not widely available with a 70% detection rate.
- CT: widely available and non invasive with a detection rate of 70% when contrast is used.
- MRI, angiography, percutaneous transhepatic portal venous sampling, arterial stimulation venous sampling and radionuclide imaging can also be used with sensitivity from 50 to 90%.
- Intraoperative sonography: equipment: not widely available with 75-90% detection rate. When using Intraoperative high frequency ultrasonography with palpation can approach 100%3
Nowadays, many noninvasive advanced imaging modalities such as MRI7, MDCT, PET, contrast-enhanced ultrasonography2, endoscopic ultrasonography6, are acclaimed to be better for preoperative localization. However these are high technology and expensive, available in medical centers of university and some advanced imaging center not inPhichitHospital.
Because of the difficulty in preoperative localization of insulinoma, in the past, almost all suspicious cases of insulinoma had to be referred to higher medical center for investigations and treatment. This caused problem of personal expense to patients and their family that some had refused and lost. On the basis of sufficient economy and sufficient medicine, we desired to investigate a case of insulinoma as best as we can.
