Importance of localization of insulinomas: a systematic analysis

Diagnostic Modalities, Management Considerations, and Outcomes of Insulinoma: A Case Series from a Tertiary Care Centre

Introduction

Insulinomas are rare, usually sporadic, and typically benign pancreatic neuroendocrine tumours. Pre-operative localization is challenging and evidence on comparative analysis of anatomic and scintigraphic modalities for pre-operative tumour localization is limited, even in contemporary series.

Methods

The current study was designed to study the clinical features and management challenges of insulinomas managed at a tertiary care centre. Clinical features, diagnosis, imaging techniques, surgical procedures, and outcomes details were collated. Pre-operative imaging techniques (CT/MRI, nuclear scintigraphy) were compared with intraoperative and histopathological findings to assess their accuracy of localization.

Results

Thirty-seven patients (15 females [42%]; median age 36 years [IQR 28-49]) were included in the study. In four patients (10.8%), the tumour occurred in the setting of multiple endocrine neoplasia type 1 (MEN 1) while the remaining were sporadic. The sensitivity of pre-operative localization was 61.5% (multiphasic CT), 66.6% (multiphasic MRI), 100% (68Ga Exendin-4 PET-CT), and 91.6% (EUS). Three patients with normal multiphasic CT had localization on 68Ga Exendin-4 PET-CT. The positive predictive value (PPV) of both Exendin-PET-CT and EUS was similar at 91.6% and 91.6%, respectively. All patients (except one with nesidioblastosis), who underwent enucleation or partial pancreatic resection, were cured.

Conclusion

68Ga Exendin-4 PET-CT based is a non-invasive imaging modality that has high sensitivity and PPV and can be used as a first-line imaging modality. The overall prognosis of these tumours is good with high cure rates attained following surgical resection.

Ectopic insulinoma: a systematic review

Knowledge of ectopic insulinomas comes from single cases. We performed a systematic review through PubMed, Web of Science, Embase, eLibrary and ScienceDirect of all cases reported in the last four decades. We also describe one unreported patient. From 28 patients with ectopic insulinoma, 78.6% were female and mean age was 55.7 ± 19.2 years. Hypoglycaemia was the first symptom in 85.7% while 14.3% complained of abdominal pain or genital symptoms. Median tumour diameter was 27.5 [15-52.5] mm and it was localised by CT (73.1%), MRI (88.9%), [68Ga]Ga-DOTA-exedin-4 PET/CT (100%), 68Ga-labelled-DOTA-conjugated somatostatin analogue PET/TC (100%), somatostatin receptor scintigraphy (40%) and endoscopic ultrasound (50%). Ectopic insulinomas were located at duodenum (n = 3), jejunum (n = 2), and one respectively at stomach, liver, appendix, rectum, mesentery, ligament of Treitz, gastrosplenic ligament, hepatoduodenal ligament and splenic hilum. Seven insulinomas were affecting the female reproductive organs: ovary (n = 5), cervix (n = 2) and remaining tumours were at retroperitoneum (n = 3), kidney (n = 2), spleen (n = 1) and pelvis (n = 1). 89.3% underwent surgery (66.7% surgery vs. 33.3% laparoscopy) and 16% underwent an ineffective pancreatectomy. 85.7% had localized disease at diagnosis and 14.3% developed distant metastasis. Median follow-up time was 14.5 [4.5-35.5] months and mortality was reported in 28.6% with median time until death of 60 [5-144] months. In conclusion, ectopic insulinomas are presented as hypoglycaemia with female preponderance. Functional imaging [68Ga]Ga-DOTA-exedin-4 PET/CT and 68Ga-labelled-DOTA-conjugated somatostatin analogue PET/TC have very high sensitivity. Clinicians should be alert to the possibility of extra-pancreatic insulinomas when classic diagnostic tests and intraoperative pancreas exploration failed to locate the tumour.

Diagnosis and Surgical Management of Insulinomas-A 23-Year Single-Center Experience

Background and Objectives: Insulinoma is a rare tumor of the Langerhans islets of the pancreas. It produces insulin and causes severe hypoglycemia with neuroglycopenic symptoms. The incidence is low, at about 1-2 per 1 million inhabitants per year. The diagnosis is based on the presence of Whipple's triad and the result of a fasting test. Surgery is the treatment of choice. Objectives: A retrospective observational study of patients operated on for insulinoma in our hospital focused on the diagnosis, the type of surgery, and complications. Materials and Methods: We retrospectively reviewed patients operated on due to insulinoma. There were 116 surgeries between 2000 and 2022. There were 79 females and 37 males in this group. A fasting test and a CT examination were performed on all the patients. Results: The average duration of the fasting test was 18 h. Insulinoma was found in the body and tail of the pancreas in more than half of the patients. Enucleation was the most frequent type of surgery. Complications that were Clavien Dindo grade III or more occurred in 18% of the patients. The most frequent complications were abscesses and pancreatic fistula. Five patients had malignant insulinoma. Conclusions: Surgery is the treatment of choice in the case of insulinomas. The enucleation of the tumor is a sufficient treatment for benign insulinomas, which are not in contact with the main pancreatic duct. Due to the low incidence of the condition, the centralization of patients is recommended.

Hypoglycemia in a Non-diabetic Patient and the Side Effects of Diazoxide Use

A low blood glucose level (less than 55 mg/dL) associated with autonomic and neuroglycopenic signs and symptoms that resolve after glucose administration establishes Whipple's triad, indicating the presence of a hypoglycemic disorder. Insulinoma remains the most common cause of endogenous hyperinsulinemia. We present the case of a 73-year-old male who was brought to the emergency department after losing consciousness. On initial assessment, severe hypoglycemia was identified and treated. No abnormalities were detected on the physical examination, initial blood tests, abdominal ultrasound and computed tomography (CT) thorax, and abdomen and pelvis. The patient had another episode of symptomatic hypoglycemia, and the blood tests performed were compatible with endogenous hyperinsulinism. The patient was started on diazoxide to prevent further hypoglycemia episodes. Magnetic resonance imaging (MRI) showed a nodular area in the cephalic region of the pancreas, and the patient was discharged with diazoxide and flash glucose monitoring. In the follow-up appointment, he presented with signs and symptoms of congestive heart failure. Endoscopic ultrasound was requested, but the patient was at high risk for complications while undergoing the procedure under anesthesia due to congestive heart failure. A ⁶⁸Gallium-DOTA-NOC positron emission tomography and computed tomography (PET-CT) was requested and confirmed the presence of a nodular area in the cephalic region of the pancreas. He was referred to general surgery for definitive treatment. Insulinoma is still a challenging medical condition. Therefore, management by a multidisciplinary team is essential. This case highlights the impact that side effects of medication used to treat this condition can have. Diazoxide was initiated to stop severe recurrent hypoglycemia; however, the patient developed congestive heart failure and was unable to undergo an endoscopic ultrasound to localize the lesion, resulting in a delay in diagnosis and definitive treatment. Diazoxide is a potent hyperglycemic drug but it can also cause fluid retention, nausea, hypertrichosis, neutropenia, and thrombocytopenia.

Insulinoma in childhood: a retrospective review of 22 patients from one referral centre

Background

Insulinomas are very rare in childhood with sparse knowledge on the clinical aspects and the presence of Multiple Endocrine Neoplasia type 1 (MEN1).

Methods

We conducted a retrospective review of patients diagnosed with insulinoma between 1995 and 2021, presenting to one referral centre in Russia. Clinical, biochemical, genetic, imaging and histological data were collected. In addition, follow-up and family data were obtained.

Results

A total of twenty-two children aged 5 to 16 years were identified. The median (range) gap between the first hypoglycaemia symptoms and diagnosis was 10 (1-46) months. Twelve children (55%) were misdiagnosed to have epilepsy and were treated with anticonvulsants before hypoglycemia was revealed. Contrast enhanced MRI and/or CT were accurate to localize the lesion in 82% (n=18). Five patients (23%) had multiple pancreatic lesions. All children underwent surgical treatment. The median (range) diameter of removed tumors was 1.5 (0.3-6) cm. Histopathological studies confirmed the presence of insulinoma in all cases. Immunohistochemical studies revealed G2 differentiation grade in 10 out of 17 cases. Two patients were diagnosed with metastatic insulinoma. One of them had metastases at the time of insulinoma diagnosis, while the other was diagnosed with liver metastases eight years after the surgery. Eight children (36%) were found to carry MEN1 mutations, inherited n=5, de novo n=1, no data, n=2. Children with MEN1 had significantly higher number of pancreatic tumors compared to sporadic cases. All of them developed additional MEN1 symptoms during the following 2-13 years. In the five patients with inherited MEN1, seven family members had hitherto undiscovered MEN1 manifestations.

Conclusions

In this large cohort of children with rare pediatric insulinomas, MEN1 syndrome and G2 tumors were frequent, as well as hitherto undiscovered MEN1 manifestations in family members. Our data emphasize the need of genetic testing in all children with insulinoma and their relatives, even in the absence of any other features, as well as the importance of a prolonged follow-up observation.

68 Ga-DOTATATE PET/CT imaging in endogenous hyperinsulinemic hypoglycemia: A tertiary endocrine centre experience

OBJECTIVE

Literature regarding utility of ⁶⁸ Ga-DOTATATE PET/CT in insulinoma localization across various subgroups [benign/malignant/multiple endocrine neoplasia-1 (MEN-1) syndrome associated] remains scarce. In this study, the performance of ⁶⁸ Ga-DOTATATE PET/CT was compared with contrast-enhanced computed tomography (CECT) and ⁶⁸ Ga-NODAGA-Exendin-4 PET/CT (whenever available) in an endogenous hyperinsulinemic hypoglycemia (EHH) cohort.

DESIGN

Retrospective audit.

PATIENTS

EHH patients [N = 36, lesions (n) = 49, final diagnosis: benign sporadic insulinoma (BSI) (N = 20), malignant insulinoma (N = 4, n = 14), MEN-1 syndrome associated insulinoma (N = 9, n = 15), Munchausen syndrome (N = 2) and drug-induced hypoglycemia (N = 1)] having both preoperative imaging modalities (CECT and ⁶⁸ Ga-DOTATATE PET/CT).

MEASUREMENTS

Per-lesion sensitivity (Sn) and positive predictive value (PPV) for histopathological diagnosis of insulinoma.

RESULTS

Sn and PPV of ⁶⁸ Ga-DOTATATE PET/CT were 67.3% and 89.2%; 55% and 100%; 85.7% and 100%; and 66.7% and 77% for overall EHH, BSI, malignant, and MEN-1 syndrome associated insulinoma cohorts respectively. Despite having comparatively lower sensitivity in BSI cohort, ⁶⁸ Ga-DOTATATE PET/CT localized a pancreatic tail lesion missed by other modalities. ⁶⁸ Ga-DOTATATE PET/CT had comparatively higher sensitivity in malignant insulinoma than BSI cohort. ⁶⁸ Ga-DOTATATE PET/CT also paved the way for successful response to ¹⁷⁷ Lu-based peptide receptor radionuclide therapy (PRRT). In MEN-1 cases, lower PPV as compared with BSI was due to uptake in non-insulinoma pancreatic neuroendocrine tumours (Pan-NET).

CONCLUSIONS

⁶⁸ Ga-DOTATATE PET/CT has supplemental role in selected cases of BSI with negative and/or discordant results with CECT and ⁶⁸ Ga-NODAGA-Exendin-4 PET/CT. In malignant insulinoma, ⁶⁸ Ga-DOTATATE-PET/CT has an additional theranostic potential. Interference due to uptake in non-insulinoma Pan-NET in MEN-1 syndrome may hinder insulinoma localization with ⁶⁸ Ga-DOTATATE-PET/CT.

A critical analysis of laparoscopic and open approaches to sporadic pancreatic insulinoma resection in the modern era

BACKGROUND

A single center experience with sporadic pancreatic insulinoma was analyzed to develop an algorithm for modern surgical management.

METHODS

Thirty-four patients undergoing surgery from 2001 to 2019 were reviewed.

RESULTS

The majority underwent enucleation (10 laparoscopic, 15 open). Laparoscopy was performed in 22 patients with conversion to open in 11, mostly related to the proximity of the tumor to the pancreatic duct (n = 4). Tumors on the anterior and posterior surface of the pancreas in all anatomic locations were completed with laparoscopic enucleation. Overall, the clinically-relevant postoperative pancreatic fistula (CR-POPF) rate was 21%, with no difference between laparoscopic versus open enucleation (10% vs 20%, p = 0.50) or enucleation versus resection (16% vs 33%, p = 0.27). Laparoscopic enucleation had shorter median hospital length of stay (LOS) compared with open (4 vs 7 days, p = 0.02).

CONCLUSIONS

Laparoscopic enucleation does not increase the CR-POPF risk and provides an advantage with a shorter hospital LOS in select patients. Tumor location and relationship to the pancreatic duct guide surgical decision-making. These findings highlight tumor-specific criteria that would benefit from a minimally invasive approach.

Large low-grade cystic pancreatic neuroendocrine neoplasm

A 58-year-old male was admitted to our hospital for a pancreatic cystic mass. Laboratory examination showed elevated levels of ALT (272 U/L, normal range, 9-50), AST (142 mg/L, normal range, 15-40), GGT (483 IU/ml, normal range, 10-60), AKP (542 U/L, normal range, 45-125), total bilirubin (21.9 U/L, normal range, 5-21), direct bilirubin (12.4 U/L, normal range, <6), CEA (7.21 ng/ml, normal range, 0-5), CA19-9 (58.91 U/ml, normal range, 0-39) and NSE (24.16 ng/ml, normal range, 0-20).

The functioning side of the pancreas: a review on insulinomas

PURPOSE

Insulinomas are a rare type of neuroendocrine tumors, originating in the pancreas, difficult to diagnose and to treat. Due to its rarity, insulinomas are a not well-known pathological entity; thus, the diagnostic process is frequently a medical challenge with many possible differential diagnoses. The diagnostic process varies between non-invasive procedures, such as the fasting test or imaging techniques, and invasive ones. Insulinomas are rarely malignant, but the glycemic imbalance correlated with this tumor can frequently alter the quality of life of the patients and the consequent hypoglycemia can be extremely dangerous. Moreover, insulinomas can be associated with different genetic syndromes, such as Multiple Endocrine Neoplasia 1, accompanied by other specific symptoms. There are many different treatment strategies, depending on the need to control symptoms or control diseases progression, the only curative one being surgery.

METHODS AND RESULTS

We reviewed the evidences present in the literature on insulinomas and reported its main clinical characteristics and management strategies.

CONCLUSION

The aim of this review of the literature is to present the current knowledge on insulinomas, exploring the main clinical characteristics, the diagnostic tools, and the therapeutic strategies.

Clinical Characteristics and Management of Functional Pancreatic Neuroendocrine Neoplasms: A Single Institution 20-Year Experience with 286 Patients

BACKGROUND

Functional pancreatic neuroendocrine neoplasms (PanNENs) are very rare disorders but have complex spectrum, including insulinoma, gastrinoma, glucagonoma, somatostatinoma, and VIPoma. Patients with PanNENs usually present with characteristic symptoms caused by corresponding hormone hypersecretion. It has always been challenging in dealing with such rare but complicated disorders. In this report, we analyzed the clinical characteristics of functional PanNENs in a large cohort of Chinese patients and summarized our clinical experience in diagnosis and treatment.

METHODS

The retrospective analysis was performed in patients with a definite diagnosis of functional PanNENs hospitalized in Chinese PLA General Hospital between 2000 and 2020. The clinical characteristics, surgical information, and pathological findings were extracted from their medical records and were analyzed.

RESULTS

Totally, 286 patients (gender: male 103 and female 183; age: 45.55 ± 15.23 years old) were diagnosed with definite functional PanNENs. The most frequent functional PanNENs were insulinoma (266/286) followed by glucagonoma (10/286), somatostatinoma (3/286), adrenocorticotropic hormone- (ACTH-) producing tumor (3/286), gastrinoma (2/286), and VIPoma (2/286). Nine patients were diagnosed with multiple endocrine neoplasia type 1 (MEN1) in which all the associated functional PanNENs were insulinomas. The duration from symptoms' onset to confirmed diagnosis was 3.67 ± 4.28 years. Two hundred and eighty patients with tumor localized in pancreatic or with limited metastasis underwent surgery. The symptoms associated with hormonal oversecretion were improved significantly after surgery. Five patients with unresectable metastases or tumor recurrence after surgery were administrated with systemic chemotherapy or other targeted therapies. With these various therapies, the symptoms were also partially relieved. According to findings in pathological and immunochemical examination, all the functional PanNENs were categorized into NEN-G1 (41.95%), NEN-G2 (54.90%), NEN-G3 (3.15%), and NEC-G3 (0%).

CONCLUSION

Patients with suspected functional PanNENs should have a systematic endocrine examination at diagnosis. Multidisciplinary collaborations are essential for precise diagnosis and tumor localization. A successful surgery or other targeted therapies can improve the prognosis of patients with such rare but complex disorders.