Commonly seen Pancreatic endocrinal tumour
Insulinoma Definition This is an insulin-producing tumour of the pancreas causing the clinical scenario know as Whipple's triad, i.e. symptoms of hypoglycaemia after fasting or exercise, plasma glucose levels <2.8 mmol/L and relief of symptoms on intravenous adminis- tration of glucose. Incidence Insulinomas are the most frequent of all the functioning PETs with a repoed incidence of 2-4 cases per million population per year. Insulinomas have been diagnosed in all age groups, with the highest incidence found in the fouh to the sixth decades. Women seem to be slightly more frequently affected. Pathology The aetiology and pathogenesis of insulinomas are unknown. No risk factors have been associated with these tumours. Viually all insulinomas are located in the pancreas and tumours are equally distributed within the gland. Approximately 90% are solitary and about 10% are multiple and associated with MEN 1 syndrome. Prognosis and predictive factors No markers are available that reliably predict the biological behaviour of an insulinoma. Approximately 10% are malignant. Insulinomas of <2 cm in diameter without signs of vascular invasion or metastases are considered benign. Clinical features Insulinomas are characterised by fasting hypoglycaemia and neuroglycopenic symptoms. The episodic nature of the hypoglycaemic attacks is caused by intermittent insulin secretion by the tumour. This leads to central nervous system symptoms such as diplopia, blurred vision, confusion, abnormal behaviour and amnesia. Some patients develop loss of consciousness and coma. The release of catecholamines produces symptoms such as sweating, weakness, hunger, tremor, nausea, anxiety and palpitations. Biochemical diagnosis A fasting test that may last for up to 72 hours is regarded as the most sensitive test. Usually, insulin, proinsulin, C- peptide and blood glucose are measured in 1- to 2-hour intervals to demonstrate inappropriately high secretion of insulin in relation to blood glucose. About 80% of insulinomas are diagnosed by this test, most of them in the first 24 hours. Elevated C-peptide levels demonstrate the endogenous secretion of insulin and exclude factitious hypoglycaemia caused by insulin injection. Ref: Bailey and love 27th edition Pgno : 849
Insulinoma
Somatostatinoma
Gastrinoma
Glucagonoma
G.I.T