Insulinoma: multislice CT demonstration

Imaging Findings

23 year old male presented with neuroglycopenic symptoms and a combination of hypoglycemia and endogenous hyperinsulinemia. Serological tests demonstrated glucose level of 40 mg/dL with a concomitant insulin level of 6 microU/mL, a C-peptide level exceeding 200 pmol/L, and a negative screening for sulfonylurea . Under the clinical suspicion of a neuroendocrine lesion of the pancreas, thin slice multislice spiral CT was performed in order to accurately evaluate pancreatic parenchyma.

Discussion

Gastrointestinal endocrine neoplasms are rare tumours that have been classified by the peptides they secrete and the resulting clinical syndromes. Endocrine tumors of the pancreas are slowly growing tumors the most common of which is insulinoma, followed by non-functioning tumors and gastrinoma.. Insulinomas are usually benign tumors originating from the pancreatic islets ; since they are biologically active tumors, insulinomas present clinically with hypoglycemia caused by increased insulin production.. Usually they are single, and small, and are generally firmer than surrounding normal pancreas. Malignant insulinomas appear in 10% of cases. Tumor size, gross invasion, and metastases correlated significantly with tumor behavior and allowed us to distinguish between "benign" and "malignant" tumor . Insulinomas may occur at every age, but mainly about the 50th year. To make a diagnosis of insulinoma, one must consider clinical manifestation . Except in MEN 1syndrome, in which a more extensive resection is usually indicated, excision of a single benign insulinoma leads to long-term cure of the disease. Tumors in the head of the pancreas are usually enucleated, and pancreato-duodenectomy is rarely performed. The successful excision of an insulinoma will profoundly affect a patient's life. Because of its small size (a diameter of 1-2 cm) diagnostic localization is often difficult. In order to localize the tumor and to search for metastasis, several imaging studies can be used.. We examined one patients with clinically suspected insulinoma with multislice CT to investigate its capabilities on identifying and characterizing this type of lesion. Images of the pancreas were obtained using 1 mm collimation on arterial and portal venous phase following the rapid injection of contrast medium. Scanning time was 20 s. Acquisition of the arterial phase and late phase were started at 18 s ( starting from the diaphragm ) and 60 s respectively, after injection of 140 ml of contrast medium at a rate of 4 ml/s. High resolution arterial phase acquisition of the pancreas is very valuable in the detection of small insulinomas. Multislice CT scanning during the arterial phase and retrospective multidimensional reformation of the volume data set is useful for preoperative detection and localization of small islet cell tumors of the pancreas. Multiplanar and 3D reconstructions were not necessary for lesion identification, but we used them for regional vascular mapping.. Volume rendering reconstructions demonstrates the lesion with information of their relationship with vascular structures.

Differential Diagnosis List

Final Diagnosis

Pancreatic insulinoma

URL:	https://eurorad.org/case/728
DOI:	10.1594/EURORAD/CASE.728
ISSN:	1563-4086