Insulinoma overview
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Parminder Dhingra, M.D. [2]
Overview
An insulinoma is a tumour of the pancreas derived from the beta cells which while retaining the ability to synthesize and secrete insulin is autonomous of the normal feedback mechanisms. Patients present with symptomatic hypoglycemia which is ameliorated by feeding. The diagnosis of an insulinoma is usually made biochemically with low blood sugar, elevated insulin, pro-insulin and C-peptide levels and confirmed by medical imaging or angiography. The definitive treatment is surgery. Pancreatic islet cells was first described by Paul Langerhans in 1869, while he was still a medical student. Insulin was first discovered by Frederick Banting and Charles Best in 1922 from a dog’s pancreas. In 1927, William J Mayo was the first to discover the association between hyperinsulinism and a functional pancreatic islet cell tumor. In 1929, Roscoe Graham was the first to perform surgical cure of an islet cell tumor. On microscopic histopathological analysis, solid or gyriform patterns, usually without glands are characteristic findings of insulinoma. Insulinoma may occur as part of other genetic syndromes such as multiple endocrine neoplasia type 1 and von Hippel-Lindau syndrome. Insulinoma must be differentiated from autoimmune hypoglycemia, hypoglycemia due to sulfonylurea or insulin abuse, factitious hypoglycemia, noninsulinoma pancreatogenic hypoglycemia syndrome (NIPHS), familial persistent hyperinsulinemia, and nesidioblastosis.[1] The incidence of insulinoma is approximately 0.1 to 0.4 per 100,000 individuals worldwide. There is no racial predilection to the insulinoma. Females are more commonly affected with insulinoma than males.[2] The male to female ratio is approximately 2 to 3. The median age at diagnosis is 45.5 years.[2] Common risk factors in the development of insulinoma include family history of multiple endocrine neoplasia type 1 and von Hippel-Lindau syndrome, rural population, female gender, and age (40 years or older). According to the the U.S. Preventive Service Task Force (USPSTF), there is insufficient evidence to recommend routine screening for insulinoma.[3] If left untreated, patients with insulinoma may progress to develop autonomic symptoms, neuroglycopenenic symptoms, and symptoms of catecholaminergic response. According to The American Joint Committee on Cancer (AJCC), there are four stages of insulinoma based on the TNM staging sysytem. Symptoms of insulinoma include diaphoresis, palpitations, confusions, seizures, sweating, tachycardia, and anxiety. A positive family history of multiple endocrine neoplasia type 1 or von Hippel-Lindau syndrome may be present. Common physical examination findings of insulinoma include tachycardia, jaundice, diplopia, tremors, and altered mental status. Laboratory findings consistent with the diagnosis of insulinoma include 72h suppression test and Whipple's triad. Findings on abdominal CT scan suggestive of insulinoma include calcification and hyper attenuation on arterial phase.[4] Findings on abdominal MRI suggestive of insulinoma include signal enhancement on T1 C+ (Gd).[5] Abdominal ultrasound scan may be helpful in the diagnosis of insulinoma. Findings on ultrasound scan suggestive of insulinoma are homogeneously hypoechoic, rounded in shape, and with distinct margins.[6] Other imaging studies for insulinoma include indium-111 pentetreotide scan. Other diagnostic studies for insulinoma include intra-arterial calcium stimulation test with hepatic venous sampling. The predominant therapy for insulinoma is surgical resection. Supportive therapy for insulinoma includes octerotide, endoscopic ultrasound guided alcohol ablation, radiofrequency ablation, embolization, diazoxide and chemotherapy. Surgery is the mainstay of treatment for insulinoma. The feasibility of surgery depends on the stage of insulinoma at diagnosis.[6][7] There is no established method for prevention of insulinoma.
Historical Perspective
Pancreatic islet cells was first described by Paul Langerhans in 1869, while he was still a medical student. Insulin was first discovered by Frederick Banting and Charles Best in 1922 from a dog’s pancreas. In 1927, William J Mayo was the first to discover the association between hyperinsulinism and a functional pancreatic islet cell tumor. In 1929, Roscoe Graham was the first to perform surgical cure of an islet cell tumor.
Pathogenesis
On microscopic histopathological analysis, solid or gyriform patterns, usually without glands are characteristic findings of insulinoma. Insulinoma may occur as part of other genetic syndromes such as multiple endocrine neoplasia type 1 and von Hippel-Lindau syndrome.
Causes
There are no established causes for insulinoma.
Differential Diagnosis
Insulinoma must be differentiated from autoimmune hypoglycemia, hypoglycemia due to sulfonylurea or insulin abuse, factitious hypoglycemia, noninsulinoma pancreatogenic hypoglycemia syndrome (NIPHS), familial persistent hyperinsulinemia, and nesidioblastosis.[1]
Epidemiology and Demographics
The incidence of insulinoma is approximately 0.1 to 0.4 per 100,000 individuals worldwide. There is no racial predilection to the insulinoma. Females are more commonly affected with insulinoma than males.[2] The male to female ratio is approximately 2 to 3. The median age at diagnosis is 45.5 years.[2]
Risk Factors
Common risk factors in the development of insulinoma include family history of multiple endocrine neoplasia type 1 and von Hippel-Lindau syndrome, rural population, female gender, and age (40 years or older).
Screening
According to the the U.S. Preventive Service Task Force (USPSTF), there is insufficient evidence to recommend routine screening for insulinoma.[8]
Natural History, Complications and Prognosis
If left untreated, patients with insulinoma may progress to develop autonomic symptoms, neuroglycopenenic symptoms, and symptoms of catecholaminergic response.
Staging
According to The American Joint Committee on Cancer (AJCC), there are four stages of insulinoma based on the TNM staging sysytem.
History and Symptoms
Symptoms of insulinoma include diaphoresis, palpitations, confusions, seizures, sweating, tachycardia, and anxiety. A positive family history of multiple endocrine neoplasia type 1 or von Hippel-Lindau syndrome may be present.
Physical Examination
Common physical examination findings of insulinoma include tachycardia, jaundice, diplopia, tremors, and altered mental status.
Laboratory Findings
Laboratory findings consistent with the diagnosis of insulinoma include 72h suppression test and Whipple's triad.
CT
Findings on abdominal CT scan suggestive of insulinoma include calcification and hyper attenuation on arterial phase.[4]
MRI
Findings on abdominal MRI suggestive of insulinoma include signal enhancement on T1 C+ (Gd).[5]
Ultrasonography
Abdominal ultrasound scan may be helpful in the diagnosis of insulinoma. Findings on ultrasound scan suggestive of insulinoma are homogeneously hypoechoic, rounded in shape, and with distinct margins.[6]
Other Imaging Findings
Other imaging studies for insulinoma include indium-111 pentetreotide scan.
Other Diagnostic Studies
Other diagnostic studies for insulinoma include intra-arterial calcium stimulation test with hepatic venous sampling.
Medical Therapy
The predominant therapy for insulinoma is surgical resection. Supportive therapy for insulinoma includes octerotide, endoscopic ultrasound guided alcohol ablation, radiofrequency ablation, embolization, diazoxide and chemotherapy.
Surgery
Surgery is the mainstay of treatment for insulinoma. The feasibility of surgery depends on the stage of insulinoma at diagnosis.[6][7]
Primary Prevention
There is no established method for prevention of insulinoma.
Secondary Prevention
There are no secondary preventive measures available for insulinoma.
References
- ↑ 1.0 1.1 Abboud, Bassam (2008). "Occult sporadic insulinoma: Localization and surgical strategy". World Journal of Gastroenterology. 14 (5): 657. doi:10.3748/wjg.14.657. ISSN 1007-9327.
- ↑ 2.0 2.1 2.2 2.3 Vázquez Quintana E (2004). "The surgical management of insulinoma". Bol Asoc Med P R. 96 (1): 33–8. PMID 15575328.
- ↑ USPTF.http://www.uspreventiveservicestaskforce.org/BrowseRec/Search?s=insulinoma
- ↑ 4.0 4.1 Insulinoma. Dr Yuranga Weerakkody and Dr Frank Gaillard et al. Radiopaedia 2015. http://radiopaedia.org/articles/insulinoma
- ↑ 5.0 5.1 Insulinoma. Dr Yuranga Weerakkody and Dr Frank Gaillard et al. http://radiopaedia.org/articles/insulinoma accessed on 10 October, 2015.
- ↑ 6.0 6.1 6.2 6.3 Okabayashi T, Shima Y, Sumiyoshi T, Kozuki A, Ito S, Ogawa Y; et al. (2013). "Diagnosis and management of insulinoma". World J Gastroenterol. 19 (6): 829–37. doi:10.3748/wjg.v19.i6.829. PMC 3574879. PMID 23430217.
- ↑ 7.0 7.1 Inulinoma. national library of medicine. https://www.nlm.nih.gov/medlineplus/ency/article/000387.htm
- ↑ USPTF.http://www.uspreventiveservicestaskforce.org/BrowseRec/Search?s=insulinoma