Insulinoma Presenting Research Articles

Insulinoma presenting with anti-insulin antibodies.

An 89-year-old woman presented with a 6-year history of occasional episodes of impaired consciousness that were relieved by ingestion of a snack. Three months before presenting to our hospital, she had been hospitalized in a local hospital with subdural hematoma caused by a head contusion, where previously unrecognized hypoglycemia was discovered. Fasting plasma glucose concentration was 37 mg/dL, with a relatively high serum level of insulin (34.9 µU/mL). Computed tomography showed a 14 mm hyperenhancing tumor in the tail of the pancreas and she was referred to our hospital for further investigation. A prolonged fasting test revealed the plasma glucose concentration reduced to 43 mg/dL (2.4 mmol/L) at 8 h after the last meal. Serum insulin, proinsulin, and C-peptide concentrations were 21.1 µU/mL, 16.9 pmol/L, and 2.72 ng/mL, respectively. Subsequent intravenous administration of 1 mg of glucagon increased the plasma glucose concentration to 76 mg/dL (4.2 mmol/L). Moreover, the insulin-to-C-peptide molar ratio was 0.14. These data indicated the presence of insulinoma. Interestingly, serum anti-insulin antibodies were elevated (21.1 U/mL), although she had no history of taking exogenous insulin injection, alpha lipoic acid, or sulfhydryl group-containing agents. Human leukocyte antigen (HLA) typing revealed HLA-DRB1*0407 and HLA-DRB1*1405 alleles. Treatment with diazoxide prevented hypoglycemia, but was discontinued due to weight gain and leg edema. Elevated serum anti-insulin antibodies persisted almost 1 year after the diagnosis of insulinoma. We present a rare case of insulinoma concomitant with serum anti-insulin antibodies. Insulinoma presenting with concomitant anti-insulin antibodies appears rare. Insulin/C-peptide molar ratio and serum insulin concentration are useful for differentiating insulinoma and autoimmune syndrome. Flash glucose monitoring systems appear suitable for evaluating treatment outcomes.

Insulinoma presenting with asymptomatic hypoglycemia

Insulinoma presenting with asymptomatic hypoglycemia

SAT171 An Unusual Presentation Of Insulinoma With Postprandial Hypoglycemia

Abstract Disclosure: J.G. Melendez-Rivera: None. F.H. Morgan: None. A. Aneja: None. Background: Insulinomas are rare neuroendocrine tumors of the pancreas with an incidence of four cases per million individuals per year. The most common presentation of insulinoma is fasting hypoglycemia with associated neuroglycopenic symptoms. Postprandial hypoglycemia has been previously reported, usually in combination with fasting hypoglycemia. Exclusive postprandial hypoglycemia is estimated to occur in 6% of insulinomas. Clinical Case: A 61-year-old woman presented with episodes of postprandial blurry vision, diaphoresis, nausea, and dizziness occurring for the last 18 months that have become more frequent. The patient reported blood glucose measurements in the 35 - 40 mg/dL range at the time of symptoms. Fasting blood glucose levels remained consistently in the 70 - 90 mg/dL range. These symptoms were originally sporadic but progressively became more common to the point that they were occurring daily after meals, and she gained 20 pounds due to increased food intake. BMI was 36.28. Her physical exam was unremarkable. Fasting labs revealed a glucose of 82mg/dl and C-peptide of 2.8ng/ml with normal cortisol. After a short trial of a reactive hypoglycemia diet, the patient had no improvement in symptoms, and was admitted for a 72-hour fast. She developed hypoglycemia with a glucose of 42mg/dl within four hours of starting her inpatient fast. At the time of hypoglycemia, insulin and C-peptide were inappropriately normal (insulin 15.9 mIU/mL and C-peptide 2.57 ng/mL) with an elevated proinsulin (42.3 pmol/L). An MRI abdomen with and without IV contrast showed a 16 mm hypervascular mass in the head of the pancreas. She subsequently underwent endoscopic ultrasonography with fine needle aspiration showing findings consistent with a well-differentiated pancreatic neuroendocrine tumor. Ga-68 DOTATATE PET CT revealed increased DOTATATE avidity in the pancreatic head mass compatible with neuroendocrine tumor but no evidence of metastatic disease. She underwent surgical resection of the tumor with resolution of symptoms. Conclusion: The absence of fasting hypoglycemia does not rule out pancreatic neuroendocrine tumors. While rare, exclusive postprandial hypoglycemia can be seen in these types of tumors, especially proinsulin-secreting tumors. This case illustrates the importance of considering insulinoma during the evaluation of postprandial hypoglycemia in the absence of fasting hypoglycemia and persistent hypoglycemia despite dietary modifications. Presentation: Saturday, June 17, 2023

FRI361 Insulinoma Presenting With Complete Heart Block

Abstract Disclosure: R. Campbell: None. S.J. Lawless: None. B. MacNeill: None. E. Brosnan: None. M.J. Bell: None. Background: Insulinomas are a rare functioning pancreatic neoplasm, causing hypoglycaemia, typically during the fasting state (1). The non-specific and varied presentations of this condition make it quite the elusive diagnosis. Clinical Case: A 32 year old female with multiple presentations to the hospital with loss of consciousness and fatigue was subsequently noted to have complete heart block with a 4.4 second pause due to ventricular standstill in the early morning on a holter monitor. She had a background history of temporal lobe epilepsy from the age of 17 and was on regular anti-epileptics. Following discussion with the electrophysiology team, a dual chamber pacemaker (PPM) was inserted. Two months following PPM insertion she was re-admitted with another collapse, however on this occasion a blood glucose level (BGL) was 1.7mmol/L, promoting investigation for a possible insulinoma. A 72hr fast provided biochemical evidence of same with a BGL of 1.6mmol/L within 24hrs, insulin level 72.7pmol/L and c-peptide 621pmol/L. She was commenced on Octreotide and Diazoxide while awaiting further work-up. A CT pancreas was normal, and she subsequently underwent an endoscopic ultrasound, which visualised an isoechoic lesion in the pancreatic mid-body. One year following her initial presentation she underwent enucleation of the pancreatic lesion and pathology confirmed an insulinoma. Her symptoms resolved and her pacemaker was subsequently removed after multidisciplinary discussion and a period of close observation with the device function turned off. Conclusion: To date there are no published case reports of an insulinoma presenting as complete heart block, however the phenomenon has been studied in animal models. Key learning points are the ambiguous nature of this diagnosis and the need to keep an open mind, particularly when other factors muddy the water, which in this case were cardiac arrhythmias and seizure disorder. Reference: (1) Okabayashi T, Shima Y, Sumiyoshi T, Kozuki A, Ito S, Ogawa Y, et al. Diagnosis and management of insulinoma. World journal of gastroenterology: WJG. 2013;19(6):829. Presentation: Friday, June 16, 2023

Continuous glucose monitoring in a patient with insulinoma presenting with unawareness of postprandial hypoglycemia.

Unawareness of postprandial hypoglycemia for 5 years was identified in a 66-year-old man at a local clinic. The patient was referred to our hospital because of this first awareness of hypoglycemia (i.e. lightheadedness and impaired consciousness) developing after lunch. In a 75 g oral glucose tolerance test, the plasma glucose concentration was decreased to 32 mg/dL (1.8 mmol/L) at 150 min with relatively high concentrations of insulin (8.1 μU/mL), proinsulin (70.3 pmol/L), and C-peptide (4.63 ng/mL). In a prolonged fasting test, the plasma glucose concentration was decreased to 43 mg/dL (2.4 mmol/L) at 66 h with an insulin concentration of 1.4 μU/mL and a C-peptide concentration of 0.49 ng/mL. Computed tomography showed an 18 mm hyperenhancing tumor in the uncinate process of the pancreas. A selective arterial calcium stimulation test showed an elevated serum insulin concentration in the superior mesenteric artery. The patient was then diagnosed with insulinoma and received pancreaticoduodenectomy. Continuous glucose monitoring (CGM) using the Dexcom G6 system showed unawareness of hypoglycemia mainly during the daytime before surgery. When the sensor glucose value was reduced to 55 mg/dL (3.1 mmol/L), the Dexcom G6 system emitted an urgent low glucose alarm to the patient four times for 10 days. Two months after surgery, an overall increase in daily blood glucose concentrations and resolution of hypoglycemia were shown by CGM. We report a case of insulinoma with unawareness of postprandial hypoglycemia in the patient. The Dexcom G6 system was helpful for assessing preoperative hypoglycemia and for evaluating outcomes of treatment by surgery. Insulinoma occasionally leads to postprandial hypoglycemia. The CGM system is useful for revealing the presence of unnoticed hypoglycemia and for evaluating treatment outcomes after surgical resection. The Dexcom G6 system has an urgent low glucose alarm, making it particularly suitable for patients who are unaware of hypoglycemia.

Left hemiparesis and urinary incontinence as presentation of pancreatic Insulinoma in a young female. A Case report and review of literature

Searchable abstracts of presentations at key conferences in endocrinology ISSN 1470-3947 (print) | ISSN 1479-6848 (online)

Abstract #1404146: The Ups and Downs of Diagnosing Insulinoma

Insulinomas are rare neuroendocrine tumors of the pancreas. The diagnosis of an insulinoma may be delayed in the geriatric population, as older individuals often have comorbid conditions making evaluation more difficult. The case described here involves an exceptionally rare presentation of insulinoma in a 78-year-old male with underlying type 2 diabetes mellitus and heart failure. A 78-year-old man with a past medical history of type 2 diabetes, heart failure, and chronic kidney disease presented to the hospital with bilateral lower extremity edema and shortness of breath. He had been hospitalized four times during the previous six months for acute heart failure exacerbations accompanied by recurrent episodes of hypoglycemia. Of note, his diabetes was well-controlled with glimepiride and dapagliflozin only. The patient reported symptomatic hypoglycemia, primarily during fasting episodes, with nadir serum glucose values between 40 and 50 mg/dL. During hospitalizations, total insulin (range 22-68 uU/mL), and C peptide (range 6.9-16.4 ng/mL) concentrations were inappropriately elevated when glucose was low, indicative of endogenous hyperinsulinemia. However, this hypoglycemia was thought to be secondary to recent sulfonylurea use in the setting of poor diet and acute renal insufficiency related to heart failure. Both glimepiride and dapagliflozin were held, though he inadvertently continued to take glimepiride until his fourth hospitalization. During his fourth admission, the patient continued to have symptomatic hypoglycemia. As his sulfonylurea screen was negative, he underwent an Octreoscan that revealed radiotracer uptake in the distal pancreas. An endoscopic ultrasound with biopsy revealed a well-differentiated neuroendocrine tumor of the pancreas. His heart failure made agents such as diazoxide, verapamil, and phenytoin undesirable, and he was discharged on subcutaneous octreotide three times daily with a plan to follow up in the surgery clinic. The presentation of insulinomas in the geriatric population can be variable and nonspecific, increasing the risk of misdiagnosis or delay of diagnosis. Missing the diagnosis can lead to increased morbidity and mortality via cognitive impairment and falls. Our patient experienced a delay in diagnosis of insulinoma of over one year despite satisfying the criteria of Whipple’s triad during his first admission. The patient had been asked to stop all anti-diabetic medications during his third admission. However, he misunderstood and continued glimepiride. Further, his acute renal insufficiency, heart failure, and decreased appetite provided alternative causes for his hypoglycemia. Insulinomas are extremely rare pancreatic neuroendocrine tumors that typically present in patients between 40 and 60 years of age. However, there have been reports of these rare tumors in older individuals, who often have comorbid conditions making their diagnosis more difficult. This case report highlights the importance of including insulinoma as a cause of persistent endogenous hypoglycemia among the geriatric population.

Hypoglycemia In Non-Diabetic Patient: Report of Two Cases of Insulinoma

Background: Insulinoma is a B-cell tumor of the islets of the pancreas with an incidence of 4 per 1 million people per year, which produces excess insulin and can cause symptoms related to hypoglycemia at the level of the central nervous system or symptoms related to excess release of catecholamines. The presence of hypoglycemia, elevated insulin, proinsulin, and c-peptide levels suggest endogenous hyperinsulinism, which together with imaging findings suggestive of neuroendocrine tumor, allow establishing the diagnostic impression of Insulinoma. Case Report: Patients with neuroglycopenic symptoms, biochemical profile of hypoglycemia, endogenous hyperinsulinemia and radiological finding compatible with insulinoma are reported, who were treated by surgical resection of the tumor, with complete resolution of the initial symptoms. Conclusion: The clinical presentation, diagnosis and treatment of insulinoma represents a clinical challenge, since it is a rare pathology and the delay in diagnosis can have catastrophic consequences for the patient such as permanent brain damage and death.

Insulinoma presenting as Seizures - Case Report of a 16-year-old young woman

Searchable abstracts of presentations at key conferences in endocrinology ISSN 1470-3947 (print) | ISSN 1479-6848 (online)

Diagnosis and Treatment Course of Insulinoma Presenting as Hypoglycemia Unawareness Using a Factory-Calibrated Continuous Glucose Monitoring System

Patient: Male, 35-year-old Final Diagnosis: Insulinoma Symptoms: Loss of consciousness Medication:— Clinical Procedure: — Specialty: Endocrinology and Metabolic • Metabolic Disorders and Diabetics Objective: Rare disease Background:Insulinoma presenting only with postprandial hypoglycemia is difficult to diagnose. Repeated episodes of hypoglycemia can lead to “hypoglycemia unawareness”, which can be even more dangerous and requires early detection and treatment.Case Report:We report the case of a 35-year-old man with an insulinoma presenting as postprandial hypoglycemia who was treated with diazoxide and monitored using a factory-calibrated continuous glucose monitoring (CGM) system until surgery. When the patient initially presented with hypoglycemia, relative hyperinsulinemia was present. There were no obvious abnormal findings on imaging examination. Hypoglycemia was not repeated on endocrinological examination, even while fasting. Four months later, asymptomatic postprandial hypoglycemia of 48 mg/dL was incidentally detected. Although none of the conventional 3 indicators of relative hyperinsulinemia were met, an insulinoma was suspected based on the results of a fasting test. Computed tomography and magnetic resonance imaging showed a mass in the pancreatic uncinate process, and selective intra-arterial calcium infusion revealed high insulin levels in the same area, leading to a diagnosis of insulinoma. The patient was treated medically with diazoxide, using a factory-calibrated CGM system until surgery. Subsequently, pancreatic mass enucleation was performed, and pathological examination confirmed the diagnosis. After surgery, the hypoglycemia resolved, and the blood glucose level remained within a range of 100 to 180 mg/dL, without the use of diazoxide.Conclusions:A factory-calibrated CGM system is useful for evaluating the course of medical treatment, monitoring hypoglycemic episodes during the diagnostic period, detecting unconscious hypoglycemia, monitoring the response to medical treatment, and treating insulinoma after surgery.

A rare case of insulinoma presenting with deep vein thrombosis, successfully treated with minimally invasive procedures including microwave ablation.

SummaryTreatment of insulinoma can be challenging, while surgical resection is considered the first line. When surgery is contraindicated or is refused, minimally invasive procedures such as selective arterial embolization, local ablative techniques including alcohol ablation, radiofrequency ablation and microwave ablation are being used of late. The world’s first microwave ablation of insulinoma was performed in 2015, after which there have been only a handful of reported cases. A 78-year-old female presented with painful swelling of the left lower limb. She was drowsy and was previously misdiagnosed as epilepsy when she had similar episodes since 2 years ago. She had hypoglycaemia with high serum insulin and C-peptide, and mildly high adjusted calcium, serum prolactin. MRI did not show pituitary adenoma. Lower limb venous duplex scan showed left lower limb deep vein thrombosis for which she was treated with anticoagulation. CT of the abdomen showed a tumour measuring 1.8 cm, located in the antero-superior aspect of the body of the pancreas, with the superior surface being abutted by the splenic artery and the inferior surface being 3 mm above the pancreatic duct, suggestive of an insulinoma. Selective transcatheter arterial embolization of the pancreatic tumour was attempted but was abandoned due to multiple small feeding arteries. Microwave ablation of the tumour was performed successfully. Since there was a possibility of the ablation being compromised due to the heat sink at the splenic artery, 2 mL of 99% alcohol was injected into the rim of the tumour near the artery. She was subsequently normoglycaemic. She defaulted follow up for repeat imaging of pancreas and screening for MEN1 syndrome due to the impact of the COVID-19 pandemic. Minimally invasive procedures are preferred over surgery in selected patients with insulinoma, out of which microwave ablation could be preferentially recommended due to its efficacy and minimal complications. We report the first case of MWA performed in combination with AA in successfully treating insulinoma to our knowledge. This is also the first reported case of DVT associated with isolated insulinoma prior to intervention, though it is rarely reported in MEN1 syndrome.Learning pointsNovel therapeutic minimally invasive procedures are successful in treating selected cases of insulinoma.Microwave ablation could be recommended preferentially over selective trans-arterial embolization, and radiofrequency ablation in treating insulinoma due to its efficacy and minimal complications.We report the first case of microwave ablation performed in combination with alcohol ablation in successfully treating insulinoma to our knowledge.

Hypoglycemia in Non-Diabetic Patient: Report of Two Cases of Insulinoma

Background: Insulinoma is a B-cell tumor of the islets of the pancreas with an incidence of 4 per 1 million people per year, which produces excess insulin and can cause symptoms related to hypoglycemia at the level of the central nervous system or symptoms related to excess release of compensatory catecholamines. The presence of hypoglycemia, elevated insulin, proinsulin, and c-peptide levels suggest endogenous hyperinsulinism, which together with imaging findings suggestive of neuroendocrine tumor, allow establishing the diagnostic impression of Insulinoma. Cases report: Patients with neuroglycopenic symptoms, biochemical profile of hypoglycemia, endogenous hyperinsulinemia and radiological finding compatible with insulinoma are reported, who were treated by surgical resection of the tumor, with complete resolution of the initial symptoms. Conclusion: The clinical presentation, diagnosis and treatment of insulinoma represents a clinical challenge, since it is a rare pathology and the delay in diagnosis can have catastrophic consequences for the patient, stories such as permanent brain damage and death.

Metastatic Insulinoma Presenting After Bariatric Surgery in a Patient Subsequently Diagnosed With MEN 1

Background: Hypoglycemia is a recognized complication of bariatric procedures due to changes in the gut hormonal milieu. Possible causes of hypoglycemia include dumping syndrome, nesidioblastosis and rarely insulinoma. MEN1 is a heritable disorder characterized by the occurrence of parathyroid, anterior pituitary and pancreatic islet cell tumors. Clinical Case: A 48 yo female with HTN, depression, PCOS, primary hyperparathyroidism s/p 3.5 gland parathyroidectomy 2008, facial angiofibroma 2011, obesity s/p gastric sleeve 2018, and a history of DMT2 presented with frequent episodes of hypoglycemia. DMT2 was diagnosed in 2003, but all DM drugs were withdrawn shortly after sleeve gastrectomy. One year after surgery, she started to develop primarily fasting hypoglycemia in the 40-50 mg/dl range confirmed on CGM. Symptoms included perioral numbness, diaphoresis and confusion which resolved with glucose tablets. She reported a 7 kg weight regain due to eating every 2 hours to minimize episodes but symptoms progressed. Family history was significant for HTN and DM. A 72 hour fast confirmed hyperinsulinemia with symptomatic hypoglycemia at a serum glucose of 37 mg/dl, a suppressed ß-hydroxybutyrate of 0.6 mmol/L, elevated proinsulin 7.7 ρmol/L and inappropriate normal c-peptide 0.8 ng/mL. The oral hypoglycemic panel was negative. A pancreatic protocol CT revealed a 1.2 cm heterogeneous arterial enhancing lesion in the body of pancreas, a 0.6 cm focus in the tail of pancreas, a 1.6 cm enhancing lesion in the liver and a 1.4 cm abdominal wall mass. Genetic testing was positive for MEN-1 and additional biochemical evaluation including VIP, gastrin and glucagon was negative. A pituitary MRI was unremarkable. She underwent an ex-lap, partial hepatectomy, distal pancreatectomy, splenectomy, and resection of the duodenal mass. The pancreas had multiple NETs, largest was 1.6 cm and stained positive for insulin. The liver mass demonstrated a metastatic well differentiated NET. The 1.7 cm duodenal mass was consistent with a leiomyoma. All surgical margins were negative, but focal lymphovascular and perineural invasion was identified with negative lymph nodes (0/27). She was diagnosed with a metastatic insulinoma with histopathology revealing a well differentiated neuroendocrine tumor G1, <1mitosis/2mm2, Ki-67 less than 3%, stage pT1N0M1. Hypoglycemia resolved post-operatively. Conclusion: Hypoglycemia predominantly in the fasting state, worsening shortly after bariatric surgery, or refractory to dietary or medical management should be further evaluated to exclude insulinoma. Given her medical history, there was concern for MEN-1, thus prompting genetic testing. Unlike with sporadic cases, there is a higher rate of recurrence with MEN-1 associated insulinoma. Highly unusual is also the finding of metastatic disease, occurring only in 4- 14% of all insulinoma cases.

Emergency Right Hemihepatectomy and Resection of Retroperitoneal Masses to Control Refractory Hypoglycemia from Metastatic Insulinoma Presenting 14 Years after Resection of Non-functioning Pancreatic Neuroendocrine Tumour

Introduction: Insulinoma is rare and only 5-15% are malignant. Transformation of nonfunctioning pancreatic neuroendocrine tumour (pNET) into insulinoma has only been reported in 6 cases and all happened early. We present the first case of metastatic insulinoma that presented as an emergency,14 years after previous distal pancreatectomy for non-functioning pNET, and was refractory to medical treatment. A right hemihepatectomy and resection of retroperitoneal masses was curative.

Insulinoma presenting with postprandial hypoglycemia and a low body mass index: A case report

BACKGROUNDInsulinomas are the most common type of functioning endocrine neoplasms of the pancreas presenting hypoglycemic symptoms. Patients characteristically develop symptoms while fasting, but some patients have reported symptoms only in the postprandial state. Repeated and prolonged hypoglycemic episodes can reduce the awareness of adrenergic symptoms, and patients may have amnesia, which delays diagnosis.CASE SUMMARYWe describe a case of a 24-year-old underweight patient who showed hypoglycemic symptoms for almost 6 years. Although patients with insulinoma characteristically develop symptoms while fasting, this young man had hypoglycemic symptoms up to one hour postprandially, especially after high-sugar meals and after physical activity. The fasting tests and imaging methods performed at local hospitals were evaluated as negative for abnormal results. However, brown adipose tissue exhibited increased metabolic activity, and some muscle groups had histological changes as indicated by positron emission tomography with 2-deoxy-2-[fluorine-18]fluoro-D-glucose integrated with computed tomography. Glycogen deficiency was also histologically confirmed. The patient’s symptoms progressed over the years and occurred more frequently, i.e., several times a month, and the patient had reduced awareness of adrenergic symptoms. The follow-up fasting test was positive, and the imaging results showed a tumor in the head of the pancreas. The patient underwent laparotomy with enucleation of the insulinoma.CONCLUSIONWeight gain and fasting hypoglycemia are not necessarily characteristics of insulinoma. In prolonged cases, adrenergic symptoms can be suppressed.

Metastatic insulinoma presenting 14 years after benign tumour resection: a rare case and management dilemma.

SummaryWe present a 60-year-old woman who underwent successful surgical resection (partial pancreatectomy) for a low grade non-functioning pancreatic neuroendocrine tumour (pNET), with no biochemical or radiological features of recurrence on follow-up visits for 5 years. Fourteen years after the initial surgery, she developed spontaneous severe hypoglycaemic episodes which required hospitalisation, with subsequent investigations confirming the diagnosis of a metastatic insulin-secreting pNET (insulinoma). Medical management of her severe spontaneous hypoglycaemic episodes remained challenging, despite optimum use of diazoxide and somatostatin analogue therapy. Based on a discussion at the regional neuroendocrine tumour multidisciplinary team meeting, she underwent an elective hepatic trans-arterial embolization which was unfortunately unsuccessful. She ended up requiring an emergency right hemihepatectomy and left retroperitoneal mass resection which finally stabilised her clinical condition.Learning points:Ours is only the seventh case report of a previously benign pNET presenting as a functional insulin secreting metastatic tumour. However, it is the first case report, in which the metastatic functional pNET presented after such a long hiatus (14 years).There is currently no clear consensus regarding the length of follow-up of non-functional pNET which are deemed cured post-surgical resection, with most guidelines advocating a median follow up of 5 years (1). The delayed presentation in our case suggests additional considerations should be made regarding optimal post-operative surveillance duration based on the age of the patient, location of the tumour, lymph node spread and Ki-67 index.Hepatic artery embolization and/or partial hepatectomy remains a treatment option for pNET patients with significant hepatic metastasis.

Insulinoma presenting as hypoglycemia during lactose tolerance testing: a case report

BackgroundInsulinoma is a rare functioning pancreatic endocrine tumor, typically presenting as a sporadic solitary lesion causing hypoglycemia. While these tumors can lead to marked autonomic and neuroglycopenic symptoms, the diagnosis is often delayed.Case presentationWe present a case of a 60-year-old Caucasian man presenting with a 1-year history of progressive episodic confusion and an unexpected finding of symptomatic hypoglycemia during a lactose tolerance test. Further inquiry revealed an 8-year history of more subtle episodic neuroglycopenic symptoms preceding his presentation. After additional biochemical testing suggested a diagnosis of insulinoma, abdominal imaging was performed and revealed a 1.2-cm tumor in the tail of the pancreas. Following laparoscopic resection of the tumor, the patient had complete resolution of his symptoms and maintained normal glucose levels.ConclusionsThe clinical presentation of functioning pancreatic neuroendocrine tumors can be subtle and nonspecific. As such, clinicians should remain vigilant for insulinoma when symptomatic hypoglycemia is present. To our knowledge, this is the first report of an insulinoma found after hypoglycemia was detected during lactose tolerance testing.

An Unusual Presentation of Insulinoma: Confusion With Psychiatric Symptoms

Insulinoma is a rare but common functional neuroendocrine tumor that secretes an excess amount of insulin resulting in mostly fasting hypoglycemia but can also cause postprandial hypoglycemia. It usually presents with neuroglycopenic and autonomic sympathetic symptoms that resolve following the administration of dextrose. The patients may remain symptomatic from 1 week to as long as several decades before diagnosis. Insulinoma presenting with psychiatric symptoms has been documented in case/case series reports. Laboratory findings of elevated insulin and C-peptide level in the presence of hypoglycemia and absence of plasma sulfonylurea are suggestive of the diagnosis. Localization of the tumor is essential preoperatively. Surgery usually cures most of the patients, but a minority will have a recurrence especially with malignant insulinoma. The manuscript presents a case of insulinoma presenting with psychiatric symptoms without sympathetic symptoms that led to the delay of the diagnosis for 3 months as initially thought to be related to psychiatric problems. Pancreatic insulinoma was localized by computed tomography (CT) scan and confirmed with endoscopic ultrasound (EUS). The patient underwent successful resection of the tumor, and her symptoms were completely resolved. J Med Cases. 2020;11(5):142-144 doi: https://doi.org/10.14740/jmc3477

An unusual presentation of insulinoma and the serious consequences of delayed diagnosis

Insulinomas are rare functional neuroendocrine tumours. These tumours present with symptoms of hypoglycaemia, adrenergic and neuroglycopenic symptoms. Insulinomas are usually small in size, making ...

Insulinoma Presenting as a Complex Partial Seizure: Still a Possible Misleading Factor.

Delayed diagnosis of insulinoma remains an intractable clinical challenge because the symptoms are in most cases misattributed to other disorders. In this study, a 64-year-old man presented with intermittent seizure episodes after being misdiagnosed with epilepsy and receiving anti-epileptic drugs for 4 years. During this period, the patient continued to suffer from repeated seizures. A starvation test, pancreatic enhancement CT, MRI scan, and pathological examination clinically diagnosed insulinoma, and the symptoms improved following surgical removal of the tumor. The appearance of unusual manifestations and insulinoma imaging makes it difficult to accurately diagnose the condition. This case emphasizes the need for careful reassessment of all atypical and refractory seizures for neurologists.