What should be done in an operating room when an insulinoma cannot be found?

Abstract

SummaryInsulinoma is the most common (functioning) islet cell tumour of the pancreas and is highly curable with accurate localization and precise extirpation of the often benign, solitary lesion. Although previous reports describe high success rates without pre-operative localization, more recent recognition of the overlap among causes of endogenous hyperinsulinism, coupled with the deleterious long-term effects of blind distal pancreatectomy and re-operation, mandate the need for precise pre-operative localization or regionalization of the tumour(s). If these criteria have not been met and the surgeon finds him/herself in the operating room without a localized or regionalized tumour, the operation should be concluded without resection, the diagnosis reconfirmed, and a calcium stimulation test performed. At experienced centres, this can be often carried out within 24 -48 h and the patient returned to the operating room for a gradient-guided resection. Intraoperative venous sampling for insulin might be an option in the future but its accuracy has not been validated in sufficient numbers of patients to date. Insulinoma is the most common functioning endocrine tumour of the pancreas, seen in approximately four persons per 1 000 000 persons/year. More than 90% of insulinomas are benign, solitary, and < 2 cm in diameter. Importantly, insulinomas are equally distributed throughout the gland. The female : male ratio is approximately 3 : 2. Less than 10% are seen in association with the multiple endocrine neoplasia type 1 (MEN1) syndrome, and 5-10% of tumours are malignant.1,2 Mean age at presentation is approximately 45 years.Multiple insulinomas can be seen in 2-3% of sporadic cases but are more often seen in the MEN1 syndrome; although the insulinsecreting tumour itself is very often solitary.3,4The diagnosis of insulinoma can be challenging. 5,6 Although originally considered to present only in the fasting state or with exercise, it is now known that patients with an insulinoma can present with postprandial symptoms as well. Patients may have nonspecific adrenergic symptoms, which include anxiety, sweating and palpitations, but true organic endogenous hyperinsulinism is characterized by neuroglycopaenic symptoms that include confusion, amnesia, visual disturbances, seizures and coma. The diagnosis of endogenous hyperinsulinism is dependent on the satisfaction of Whipple's triad and remains the cornerstone of the screening process: hypoglycaemia (plasma glucose < 50 mg/dl), neuroglycopaenic symptoms, and prompt relief of symptoms with the administration of glucose define Whipple's triad. 2 Once Whipple's triad has been satisfied, the patient should be fasted either formally (72-h fast) or informally (outpatient) to a plasma glucose < 50 mg/dl with concomitant documentation of inappropriate β -cell polypeptides (insulin, C-peptide, and proinsulin). With a glucose level ≤ 45 mg/dl, an insulin level ≥ 3 μ IU/ml and a C-peptide level of ≥ 200 pmol/l, the endogenous nature of the hyperinsulinism is confirmed. It is impor...

Glucagon-Like Peptide-1 Receptor PET/CT with 68Ga-NOTA-Exendin-4 for Detecting Localized Insulinoma: A Prospective Cohort Study

“…Imaging techniques are then used to localize the tumor, which is critical for diagnosis and surgical treatment. Conventional imaging procedures such as contrast-enhanced CT, MRI, and endoscopic ultrasonography (EUS) have limited accuracy in localizing insulinomas because of the small size of these tumors (1–4). The current gold standard, that is, intraoperative ultrasound with manual palpation, yields a sensitivity of only about 80% (5).…”

Anatomical localization of insulinomas: still a need to combine a set of diagnostic procedures

“…This can assist the surgeon in the most effective and minimally invasive therapeutic approach in theatre. 12 In the modern era, the pre-and intra-operative diagnostic tools make the successful localization of insulinomas an achievable goal in centers with wide and longstanding experience. 13,14 The application of new protocols and techniques is improving the sensitivity of magnetic resonance imaging for the identification of insulinomas.…”

Can Betatrophin be a New Biochemical Marker in the Diagnosis of Insulinoma?

“…Radiological imaging is helpful in distinctive diagnosis and determination of the operation procedure. Insulinoma diagnosis is supported by C peptide >0.6 ng/ml, insulin >3 µIU/mL, proinsulin >5 pmol/L, simultaneously with hypoglycemia (plasma glucose <55 mg/dl) [1,2].It is suggested in this editorial that measuring plasma concentrations of betatrophin [3], in addition to the classical parameters used to detect insulinoma through biochemistry, can help diagnosis. Insulinoma originates from the β cells of Langerhans islets [1].…”

“…Radiological imaging is helpful in distinctive diagnosis and determination of the operation procedure. Insulinoma diagnosis is supported by C peptide >0.6 ng/ml, insulin >3 µIU/mL, proinsulin >5 pmol/L, simultaneously with hypoglycemia (plasma glucose <55 mg/dl) [1,2].…”