Giant insulinoma: a report of 3 cases and review of the literature

Case Report: Giant insulinoma, a very rare tumor causing hypoglycemia

Insulinomas, with an incidence of 4 cases per million individuals per year, remain amongst the most frequent functional neuroendocrine tumors. The usual diameter of insulinomas usually remains under 3 cm of major axis. However, 44 exceptional cases of "giant insulinomas", have been reported worldwide, generally exceeding 9 cm in major axis. In this article, we report the case of a 38-year-old woman whom suffered from chronic hypoglycemia despite treatment with diazoxide. Abdominal CT-scan revealed a 88 x 73 mm mass located at the tail of the pancreas. Following surgical excision, histopathological analysis confirmed G1 neuroendocrine tumor, with focal cytoplasmic expression of insulin in tumor cells. After a 16-month follow-up period, the patient didn't address any specific complaint, and no disease recurrence and/or metastasis were observed. A ⁶⁸Ga-DOTATATE-PET scan was performed 6 months after surgery, which came back normal. Genetic evaluation has not been performed in our patient. The physiopathology of giant insulinomas remain unexplained, however with possible relationship with type 1 multiple endocrine neoplasia, sporadic somatic YY1 mutations and possible transformation of bulky non-functional pancreatic neuroendocrine tumors to a functional phenotype, with slow insulin secretion. While giant insulinomas remain rare in the literature, multicentric genetic analysis of tumor samples might reveal unique features of this rare subtype of neuroendocrine pancreatic tumors. Insulinomas of large size tend to have greater malignancy and higher rates of invasiveness. Careful follow-up, especially for liver and lymph node metastases, must be performed using functional imaging techniques to avoid disease relapse.

Neuroendocrine Tumors of the Gastrointestinal Tract and Pancreas

Neuroendocrine neoplasms (NENs) of the gastrointestinal (GI) tract and pancreas are a rare and heterogeneous group of neoplasms characterized by common cellular features as well as unique site-specific traits. GI and pancreatic NENs are much rarer than the more common adenocarcinomas arising at these sites. However, the incidences of GI and pancreatic NENs have increased significantly, particularly in the stomach and common site, followed by rectum, appendix, colon, and stomach. Pancreatic NENs are also uncommon, with fewer than 1 per 100,000, accounting for 1% to 2% of all pancreatic neoplasms.

Surgical Management, Preoperative Tumor Localization, and Histopathology of 80 Patients Operated on for Insulinoma

INTRODUCTION

Diagnosis and pathological classification of insulinomas are challenging.

AIM

To characterize localization of tumors, surgery outcomes, and histopathology in patients with insulinoma.

METHODS

Patients with surgically resected sporadic insulinoma were included.

RESULTS

Eighty patients were included. Seven had a malignant tumor. A total of 312 diagnostic examinations were performed: endoscopic ultrasonography (EUS; n = 59; sensitivity, 70%), MRI (n = 33; sensitivity, 58%), CT (n = 55; sensitivity, 47%), transabdominal ultrasonography (US; n = 45; sensitivity, 40%), somatostatin receptor imaging (n = 17; sensitivity, 29%), 18F-fluorodeoxyglucose positron emission tomography/CT (n = 1; negative), percutaneous transhepatic venous sampling (n = 10; sensitivity, 90%), arterial stimulation venous sampling (n = 20; sensitivity, 65%), and intraoperative US (n = 72; sensitivity, 89%). Fourteen tumors could not be visualized. Invasive methods were used in 7 of these 14 patients and localized the tumor in all cases. Median tumor size was 15 mm (range, 7 to 80 mm). Tumors with malignant vs benign behavior showed less staining for insulin (3 of 7 vs 66 of 73; P = 0.015) and for proinsulin (3 of 6 vs 58 of 59; P < 0.001). Staining for glucagon was seen in 2 of 6 malignant tumors and in no benign tumors (P < 0.001). Forty-three insulinomas stained negative for somatostatin receptor subtype 2a.

CONCLUSION

Localization of insulinomas requires many different diagnostic procedures. Most tumors can be localized by conventional imaging, including EUS. For nonvisible tumors, invasive methods may be a useful diagnostic tool. Malignant tumors showed reduced staining for insulin and proinsulin and increased staining for glucagon.

Notch pathway inhibition targets chemoresistant insulinoma cancer stem cells

Insulinomas (INS) are the most common neuroendocrine pancreatic tumours in humans and dogs. The long-term prognosis for malignant INS is still poor due to a low success rate of the current treatment modalities, particularly chemotherapy. A better understanding of the molecular processes underlying the development and progression of INS is required to develop novel targeted therapies. Cancer stem cells (CSCs) are thought to be critical for the engraftment and chemoresistance of many tumours, including INS. This study was aimed to characterise and target INS CSCs in order to develop novel targeted therapies. Highly invasive and tumourigenic human and canine INS CSC-like cells were successfully isolated. These cells expressed stem cell markers (OCT4, SOX9, SOX2, CD133 and CD34), exhibited greater resistance to 5-fluorouracil (5-FU) and demonstrated a more invasive and tumourigenic phenotype in vivo compared to bulk INS cells. Here, we demonstrated that Notch-signalling-related genes (NOTCH2 and HES1) were overexpressed in INS CSC-like cells. Protein analysis showed an active NOTCH2-HES1 signalling in INS cell lines, especially in cells resistant to 5-FU. Inhibition of the Notch pathway, using a gamma secretase inhibitor (GSI), enhanced the sensitivity of INS CSC-like cells to 5-FU. When used in combination GSI and 5-FU, the clonogenicity in vitro and the tumourigenicity in vivo of INS CSC-like cells were significantly reduced. These findings suggested that the combined strategy of Notch signalling inhibition and 5-FU synergistically attenuated enriched INS CSC populations, providing a rationale for future therapeutic exploitation.

A Clinicopathological Study of Malignant Insulinoma in a Contemporary Series

OBJECTIVE

The aim of the study was to address the origin and natural history of malignant insulinoma.

METHODS

Retrospective review of medical records of patients diagnosed with insulinoma at Cedars-Sinai Medical Center between 2000 and 2015 was conducted. Hormonal expression in tumor specimens was examined by immunostaining.

RESULTS

All the 9 patients with malignant insulinoma (35% of 26 patients with insulinoma) already had liver metastasis at hypoglycemia presentation with bulky cumulative tumor burden. Six patients had de novo diagnosis, 2 had known metastatic nonfunctioning pancreatic neuroendocrine tumor, and 1 had a known pancreatic mass. Tumor grade at presentation was G1 in 4 patients, G2 in 4, and unknown in 1. Four patients died 2 to 32 months after presentation, all with extensive liver tumor involvement. Tumor expression of proinsulin and insulin was heterogeneous and overall infrequent. The proinsulin levels and proinsulin/insulin molar ratio in patients with malignant versus benign insulinoma were 334 versus 44 pmol/L and 2.1 versus 0.9, respectively.

CONCLUSIONS

Malignant insulinoma seems to arise from and behave like nonfunctioning pancreatic neuroendocrine tumor oncologically but with metachronous hyperinsulinemic hypoglycemia. High proinsulin levels and proinsulin/insulin molar ratio may suggest malignant insulinoma.

Giant insulinoma: report of a case and review of published reports

Background

Larger insulinomas are reportedly more likely to be malignant; however, their biological behavior has not been clearly elucidated. We here report the characteristics and treatment of a giant insulinoma with local invasion and lymph node metastasis. We also review published reports concerning the clinical features of giant insulinomas and comparing their grading with that of pancreatic neuroendocrine tumors.

Case presentation

A 71-year-old man was referred to our hospital for investigation of persistent hypoglycemia. On the current presentation, laboratory tests showed serum glucose, immunoreactive insulin, and C peptide concentrations of 45 mg/dL, 17.2 μIU/mL and 4.1 ng/mL, respectively. Dynamic magnetic resonance imaging showed a hypervascular tumor measuring 13.5 cm in the head of the pancreas. Computed tomography scanning demonstrated local invasion and lymph node involvement. He thus had Whipple’s triad, which is associated with malignant insulinoma. No distant metastases having been identified, pancreaticoduodenectomy was performed. Intraoperatively, three separate tumors were identified in the pancreatic head. Pathological examination showed all three tumors were pancreatic neuroendocrine tumors; the tumor cells in the largest mass were strongly immunoreactive for insulin. The Ki-67 index was 2–5% in most parts of the largest tumor and over 20% in the poorly differentiated areas. This tumor was classified as neuroendocrine carcinoma in accordance with the 2010 World Health Organization classification of pancreatic endocrine neoplasms. He remains free of evidence of recurrence 2 years postsurgery.

A review of published reports indicated that giant insulinomas are more malignant than smaller ones, and metastatic disease is found on presentation in 56% of patients with giant insulinomas; however, we were unable to identify any correlation between grade of pancreatic neuroendocrine tumor and biological behavior of giant insulinomas.

Conclusions

Giant insulinomas more frequently exhibit malignant behavior, such as local invasion, lymph node involvement, and liver metastasis, than smaller ones. However, there was no relationship between grade and rate of metastases or survival in this small case series. Identification of useful biological markers is necessary.

Concomitant existence of pheochromocytoma in a patient with multiple endocrine neoplasia type 1

Background

Multiple endocrine neoplasia type 1 (MEN1) is an autosomal-dominant inherited disorder that is classically characterized by the presence of neoplastic lesions of the parathyroid glands, the anterior pituitary gland, and the pancreas. However, MEN1 with concomitant pheochromocytoma is extremely rare.

Case report

We report a case of MEN1 concomitant with pheochromocytoma. A 44-year-old Japanese man, who had undergone total parathyroidectomy due to primary hyperparathyroidism at the age of 18, was referred to our hospital with a complaint of a large abdominal tumor. He was diagnosed as having a giant insulinoma (maximum diameter 18 cm) in the pancreatic tail, five other non-functional neuroendocrine tumors in the pancreatic body and tail, multiple liver metastases of pancreatic neuroendocrine tumors, a pituitary prolactinoma, non-functional adrenal cortical adenomas, a pheochromocytoma in addition to a subcutaneous neurofibroma, and a cutaneous fibroma. The genetic screening revealed a deletion mutation at codons 83–84 in exon 2 of the MEN1 gene. He underwent distal pancreatectomy, splenectomy, cholecystectomy, right adrenalectomy, abdominal subcutaneous tumor excision, and cutaneous tumor biopsy for the purpose of tumor volume reduction. Extended right posterior segmentectomy with partial hepatectomy of S2, S3, and S8 was performed to resect residual tumors 9 months after the initial surgery. Although a newly formed liver metastasis was found 19 months after the hepatectomy, he is still alive 4 years and 4 months after the initial surgery.

Conclusions

We reported an extremely rare case of giant insulinoma and simultaneous occurrence of pheochromocytoma and adrenal cortical adenoma in the ipsilateral adrenal gland in a patient clinically and genetically diagnosed as having MEN1.

Diagnosis and surgical management of insulinomas in 33 consecutive patients at a single institution

PURPOSE

The purpose of this study was to evaluate the diagnosis and surgical management of insulinomas in a single-center setting.

METHODS

Demographic details, clinical presentation, preoperative diagnosis, surgical strategy, and outcomes of 33 consecutive patients who underwent surgery for insulinoma were analyzed retrospectively.

RESULTS

The median time from the first onset of symptoms to diagnosis was 24 months (range 3 days to 50 years). All cases presented with Whipple's triad and had a fasting insulin to glucose ratio higher than 0.33. The preoperative detection rates of transabdominal ultrasonography, CT, MRI, and EUS were 22 % (2/9), 72 % (23/32), 75 % (9/12), and 80 % (4/5), respectively. Intraoperative manual palpation localized all cases. Enucleation was performed in 58 % of cases (19/33), partial pancreatic resection in 39 % (13/33), and enucleation plus partial resection in 3 % (1/33). Pancreatic fistula was the most common complication and occurred in 15 patients (45 %), including seven grade A, five grade B, and three grade C fistulas. There was no mortality. When compared with partial pancreatectomy, enucleation held a significant advantage in operative time and operative bleeding, with no significant differences in demographic data and postoperative complications. During a median follow-up period of 32 months, two patients were lost to follow-up and the remaining 31 patients were without evidence of recurrence.

CONCLUSIONS

A fasting insulin release index larger than 0.3 is a reliable indicator for the diagnosis of insulinoma. Intraoperative palpation by an experienced surgeon can effectively complement an uncertain preoperative localization. Compared with partial pancreatic resection, enucleation showed significant benefit in terms of intraoperative blood loss and operation time.

Different Hormonal Expression Patterns Between Primary Pancreatic Neuroendocrine Tumors and Metastatic Sites

OBJECTIVES

Pancreatic neuroendocrine tumors (PNETs) are known to have heterogeneity in terms of their ability to produce multiple hormones. The aim of this study was to evaluate the heterogeneity of PNETs from the viewpoint of hormonal expression.

METHODS

The expressions of 4 representative hormones, gastrin, insulin, glucagon, and somatostatin, in both primary and metastatic lesions, were analyzed by immunohistochemical staining in 20 patients with metastatic PNETs (6 gastrinomas, 1 insulinoma, 1 glucagonoma, and 12 nonfunctioning PNETs [NF-PNETs]). Metastatic sites included lymph nodes in all 20 patients and liver metastasis in 7 patients (2 gastrinomas and 5 NF-PNETs).

RESULTS

There were 6 PNETs with multiple hormone secretion (30%), and positive expression of 1 or more hormones was found in 9 of 12 patients whose primary tumors were diagnosed as NF-PNETs. The positive concordance rate of the hormonal expression pattern between primary tumors and metastatic lymph nodes and between primary tumors and hepatic metastasis were 50% and 11%, respectively. Three patients had metastatic lesions with positive hormonal expression, whereas their primary tumors were negative.

CONCLUSIONS

Hormonal expressions are often different between the primary tumors and metastatic sites of PNETs.

Giant insulinoma in a 15-year-old man: A case report

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Giant insulinomas are extremely rare, especially among young patients.

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Tumor resection is the treatment of choice for giant insulinomas with benign features.

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Long-term follow-up is essential in benign giant insulinoma to detect the recurrence in the future

Introduction

Giant insulinomas are extremely rare pancreatic neuroendocrine tumor.

Presentation of case

A 15-year-old man presenting with acute onset of lightheadedness was found to have serum glucose of 1.5 mmol/L. The blood collected from the hypoglycemic episode showed an inappropriately high insulin and C-peptide level. Abdominal computerized tomography showed a 12.5 cm well-defined, lobulated hypervascular mass at pancreatic tail, without any evidence of metastasis. En bloc resection with distal pancreatectomy, and splenectomy was successfully performed. The pathological examination confirmed insulinoma, with benign characteristics. Follow-up after the procedure revealed neither hypoglycemic, nor hyperglycemia.

Conclusion

We report the youngest case of a giant insulinoma. Despite the size of the tumor, the pathological report confirmed the benign characteristics. However, long-term follow-up is still essential to detect recurrence in the future.