Insulinoma: Presenting as hypoglycemia in a non-diabetic patient: A rare case report

Abstract

PNETs (pancreatic neuroendocrine tumors) are a rare sub-type of pancreatic tumors, with the majority of them being insulinomas. The vast majority of insulinomas (90%) are benign and solitary, with only 10% being malignant. It has a wide range of clinical manifestations and requires a high level of suspicion to diagnose. Surgical excision has long been the gold standard for treating localized PNET and is still the therapy of choice. Recurrent hypoglycemia is usual in diabetic patients, but this is a rare finding in non-diabetic individuals. Here, we are presenting a rare case of insulinoma who was non-diabetic and presented with recurrent hypoglycemic episodes. A 61-year-old non-diabetic male presented with multiple episodes of hypoglycemia in the past. On thorough workup, there was an increased fasting insulin level with the fasting blood glucose level ranging from 60 to 90 mg/dl. His C-peptide and proinsulin were markedly elevated. His abdominal ultrasound failed to pick up any abnormality. His DOTANOC scan revealed a 2 × 2 cm sized lesion in the distal pancreas suggestive of neuroendocrine pathology. He subsequently underwent spleen preserving distal pancreatectomy, following which his blood sugar levels remained normal, and continued to be free of symptoms on follow-up. Our instance emphasizes the need for evaluating insulinoma as a cause of recurrent hypoglycemia in people who are not diabetic. A high index of suspicion in hypoglycemic individuals who do not respond to standard treatment or whose symptom pattern changes will lower the likelihood of insulinoma diagnosis being delayed.

Keywords: DOTANOC scan; hypoglycemia; insulinoma; pancreatic neuroendocrine tumor.

Figure 1

68 Ga – DOTATOC scan showing insulinoma

Figure 2

Intraoperative picture and resected specimen showing insulinoma

Figure 3

Histology image of the pancreatic lesion