Introduction

Insulinoma is the most frequent pancreatic endocrine tumor. About one to four cases per million have been reported every year ¹. It is more common in males and can occur at any age ². It is usually benign and made up of a mass with a diameter of less than 2 cm. Insulinomas can also occur as multiple neoplasms (10 % of the cases), which are associated with the multiple endocrine neoplasia syndrome, type 1 (MEN 1). The symptoms are unspecific; therefore, treatment initiation usually delays. Patients frequently show signs of hypoglycemia because insulinomas secrete insulin ³. After clinical confirmation of hyperinsulinism, imaging staging—which is usually complicated—is carried out. The curative treatment for insulinoma is resective surgery, in spite of the fact that surgical localization is usually a diagnostic dilemma if there are not devices to perform an intraoperative ultrasound.

This case report describes the treatment for insulinoma at Hospital Nacional Arzobispo Loayza in Lima.

Clinical case

A 51-year-old female patient who went to Hospital Loayza in March 2012. She had been sick for two years, and her disease was characterized by fainting, particularly at night after dinner. There was not a history of pancreatic diseases in her family. When she was admitted to the hospital, she had hypoglycemia—with a blood sugar level of 50 mg/dl—and for this reason she underwent insulin testing, the result of which was 80 IU (range 25 IU higher). She was prescribed prolonged fasting, and hypoglycemia associated with hyperinsulinism was observed. In addition, the C-peptide level was elevated. An MRI scan was carried out (Figure 1), which revealed a nodular lesion in the anterior side of the pancreas with a diameter of approximately 2 cm. Hormones such as cortisol and thyroid hormone were measured to rule out MEN syndrome.

Figure 1 MRI scan of the patient: pancreatic lesion suggesting insulinoma 

The patient underwent open surgery with a mediumsized supraumbilical incision, which allowed opening the omental bursa (Figure 2). The lesion could be observed directly; therefore, more intraoperative images were not required. Bimanual palpation of the pancreas was carried out applying an extended Kocher maneuver to assess the lesion depth.

Figure 2 Nodular lesion of approximately 2 cm 

The punch biopsy technique was applied to remove the lesion, then silk suture was used (Figure 3) as anchorage, and the nodular lesion was removed with a monopolar electrocautery (Figure 4). The result was absolute hemostasis (Figure 5). Finally, the omental bursa was closed, and the cavity was then closed using a single layer closure without drains.

The surgeon removed a 2 cm tumor (Figure 6), which was sent to the laboratory, and the anatomopathological diagnosis was insulinoma. The glucose level normalized, and the patient did not show hyperinsulinism during the postoperative period or subsequent controls; therefore, she was discharged: on the sixth day without complications.

Figure 3 Application of silk sutures as anchorage for the neoplasm 

Figure 4 Removal of insulinoma with punch biopsy technique and unipolar electrocautery in spray mode 

The patient was followed-up for four years following the surgery. There was no evidence of symptoms of hyperinsulinism, and radiologic examinations did not show recurrence.

Figure 5 Absolute hemostasis following the neoplasm resection 

Discussion

Insulinomas are very rare tumors that have an unspecific clinical presentation. When reviewing different autopsies, the rate of silent insulinomas observed was 0.8 to 10 % ^4-7. When there are symptoms, patients usually have confusion, behavioral changes, visual disturbances, weakness, vertigo, syncope, fatigue, obtundation, seizures, among others ^8,9. Insulinomas are responsible for 70 to 75 % of the cases of hyperinsulinism ^10-12. An MRI scan has proven very useful in tumor localization in 47 % of cases, with a mean sensitivity of 45 % ^13,14.

This case shows clinical signs and symptoms that clearly suggest insulinoma. The diagnostic tests were appropriate, and the possibility of multiple endocrine neoplasia was ruled out. It is very rare to find this type of tumors by imaging; however, in this case the neoplasm could be identified very clearly (Figure 1). This improves the conditions for resective surgery, which when associated with appropriate surgical maneuvers such as an adequate bimanual palpation and wide enucleation, may predict good prognosis.

The partial success of insulinoma resection in Hospital Arzobispo Loayza can be mentioned, among other experiences. Moreover, there has been at least one case of nesidioblastosis ¹⁵, for which the proper treatment could not be administered to the patient.