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WeBSurg, the e-surgical reference of Laparoscopic surgery

Clinical Case

PANCREATIC INSULINOMA


D Mutter, MD, PhD, M Vix, MD, Hôpitaux Universitaires de Strasbourg, Strasbourg, France

1. Summary


Pancreatic insulinomas produce excessive amounts of insulin that may cause neurological and severe cardiovascular symptoms related to major hypoglycemia. It may be difficult to localize tumors preoperatively because of their small size, so intraoperative ultrasonography and manual palpation are important. In certain cases, tumor detection by endoscopic ultrasonography permits laparoscopic tumor enucleation.

2. Keywords


Insulinoma, coma, surgery

3. Patient


50-year-old woman

4. Past medical history


Appendectomy, episodes of hyperthyroidism 25 years earlier presently stabilized without any treatment, history of typhoid fever 30 years earlier.

5. History of present illness


The patient had presented with a hypoglycemic coma that led to a fall, complicated by luxation and fracture of the humerus. Over the last 2 years, numerous hypoglycemic episodes accompanied by loss of consciousness had occurred. These episodes had become more frequent recently, especially in the mornings, resulting in difficulty waking up.
During hospitalization for the surgical treatment of humerus fracture, the patient had had several hypoglycemic episodes (glycemia <0.5g/L).

6. Examinations


6.1. Physical examination

Normal physical examination

6.2. Laboratory examination

Fasting test over 5 hours. The test revealed hypoglycemia (glucose: 0.39 g/L), serum insulin level of 16.4 uU/mL (normal value: 2-15 uU/mL) and peptide C level of 4.7 ng/mL (normal value: 0.8-2.9 ng/mL).
Cortisol, ACTH, prolactin, thyroglobulin, catecholamine, serotonin, metanephrine and PTH levels were normal.
The hyperglycemic challenge revealed no negative feedback on peptide C levels.

6.3. Ultrasonography

Ultrasonography showed a hypo-echoic mass of 1 cm localized at the corporeo-caudal junction, at the confluence of the splenic and portal veins.

6.4. Endoscopic ultrasound

Endoscopic ultrasound confirmed the findings of conventional ultrasound.

6.5. CT scan

No lesions were identified by CT scan.

6.6. Somatostatin receptor scintigraphy

Somatostatin receptor scintigraphy did not reveal any lesions.
Control after 6 hours: chest (Figure 6.6.a)
Control after 6 hours: abdomen (Figure 6.6.b)
Control after 24 hours (Figure 6.6.c)

7. Treatment


The patient underwent open surgical intervention. A bi-subcostal incision that allowed full exposure of the pancreas and complete bi-manual palpation was performed. Intraoperative ultrasonography was carried out. By these two means, the 1 cm tumor was found at the corporeo-caudal junction. Simple enucleation followed. Intraoperative insulin measurements were done. During the intervention, insulin levels dropped from 28.8 uU/mL to 0.5 uU/mL after tumor resection. At the level of resection, bleeding was carefully controlled by the administration of biological glue. The postoperative period was uneventful.

8. Anatomopathology


Nodule of 1 x 1.2 cm, multilobulated, formed of cellular elements grouped in islets separated by vasculo-fibrous stroma. Cells contained normal nuclei devoid of mitotic activity. The tumor was partially encapsulated. Tumoral cells were marked by anti-chromogranin, anti-insulin, anti-synaptophysin and anti-cytokeratin antibodies. By contrast, they were not marked by anti-gastrin, anti-glucagon or anti-serotonin antibodies.

9. Discussion


Insulinomas are the most common pancreatic endocrine tumors. The incidence is 1-2 per million people. Except in patients with multiple endocrine neoplasia type 1 (MEN 1), insulinomas are benign (90%) and solitary tumors. They are evenly distributed between sexes. The median age at diagnosis is about 50 years, except in insulinoma patients with MEN 1, in whom the median age is less.
Insulinomas are characterized clinically by the Whipple triad including episodic fasting hypoglycemia, neurological and psychiatric symptoms that are related to hypoglycemia and are reversible by glucose administration. Other symptoms are: feelings of faintness, loss of consciousness, hypoglycemic comas and difficulty in waking up. Because of their non-specificity and intermittency, correct diagnosis is often delayed.
The diagnosis is based on biochemical parameters, that is to say, hypoglycemia associated with inappropriate secretion of insulin as evidenced by elevated peptide C levels.
Prolonged supervised fasting over 48 hours provides the most reliable results when decreased glucose levels and elevated serum insulin and C peptide levels are found. The calculation of the ratio of insulin to plasma glucose is diagnostic if it exceeds 0.6.
Preoperative tumor localization is difficult. Investigations include CT scan, MRI, somatostatin receptor scintigraphy, percutaneous and endoscopic ultrasonography and, in certain cases, preoperative portal venous sampling preceded by selective arteriography.
Endoscopic ultrasonography appears to be the most reliable tool for insulinoma detection. The tumors are distributed evenly throughout the pancreas. In more than 80% of cases, tumor size is <2 cm.
Surgical treatment combining manual palpation with intraoperative ultrasonography detects almost 100% of tumors.
Simple enucleation is the treatment of choice in most cases. Subtotal pancreatectomy may be necessary when the tumor is in contact with the main pancreatic duct. Laparoscopic techniques are possible if preoperative tumor localization is successful.

10. References


  1. Berends FJ, Cuesta MA, Kazemier G, Van Eijck CH, De Herder WW, Van Muiswinkel JM, Bruining HA, Bonjer HJ. Laparoscopic detection and resection of insulinomas. Surgery 2000 ;128:386-91.
  2. Catalano C, Pavone P, Laghi A, Panebianco V, Fraioli F, Pediconi F, Napoli A, Passariello R. Localization of pancreatic insulinomas with MR imaging at 0.5 T. Acta Radiol 1999;40:644-8.
  3. Hashimoto LA, Walsh RM. Preoperative localization of insulinomas is not necessary. J Am Coll Surg 1999;189:368-73.
  4. Iihara M, Kanbe M, Okamoto T, Ito Y, Obara T. Laparoscopic ultrasonography for resection of insolunomas .Surgery 2001;130:1086-91.
  5. Suzuki K, Takahashi S, Aiura K, Hayatsu S, Kitago M, Hoshimoto S. Kitajima M. Evaluation of the usefulness of percutaneous transhepatic portal catheterisation for preoperatively diagnosing the localization of insulinomas. Pancreas 2002;24:96-102.