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Open access

Chad Bisambar, Andrew Collier, Fraser Duthie and Carron Meney

Summary

A 40-year-old Caucasian female presented with hyperglycaemia, polyuria, polydipsia and weight loss of 6 kg over a 1-month period. There was no personal or family history of malignancy or diabetes mellitus. On examination, she was jaundiced with pale mucous membranes and capillary glucose was 23.1 mmol/L. Initial investigations showed iron deficiency anaemia and obstructive pattern of liver function tests. HbA1c was diagnostic of diabetes mellitus at 79 mmol/mol. Malignancy was suspected and CT chest, abdomen and pelvis showed significant dilatation of intra- and extra-hepatic biliary tree including pancreatic duct, with periampullary 30 mm mass lesion projecting into lumen of duodenum. Enlarged nodes were seen around the superior mesenteric artery. This was confirmed on MRI liver. Fasting gut hormones were normal except for a mildly elevated somatostatin level. Chromogranin A was elevated at 78 pmol/L with normal chromogranin B. Duodenoscopy and biopsy showed possible tubovillous adenoma with low-grade dysplasia, but subsequent endoscopic ultrasound and biopsy revealed a grade 1, well differentiated neuroendocrine tumour. The patient was started on insulin, transfused to Hb >8 g/dL and Whipple’s pancreatico-duodenectomy was undertaken. This showed a well-differentiated neuroendocrine carcinoma arising in duodenum (Grade G1 with Ki67: 0.5%), with areas of chronic pancreatitis and preservation of pancreatic islet cells. There was complete resolution of diabetes post Whipple’s procedure and patient was able to come of insulin treatment. Her last HBA1C was 31 mmol/mol, 4 months post tumour resection.

Learning points:

  • Diabetes mellitus and malignancy can be related.

  • A high index of suspicion is needed when diabetes mellitus presents atypically.

  • Non-functional neuroendocrine tumours can present with diabetes mellitus.

Open access

Yasutaka Takeda, Yukihiro Fujita, Kentaro Sakai, Tomoe Abe, Tomonobu Nakamura, Tsuyoshi Yanagimachi, Hidemitsu Sakagami, Jun Honjo, Atsuko Abiko, Yuichi Makino and Masakazu Haneda

Summary

MEN1-associated pancreatic neuroendocrine tumors (pNETs) may potentially express distinct hormones, but the mechanism has not been elucidated. Transcription factors such as MafA and Pdx1 have been identified to lead to beta cell differentiation, while Arx and Brn4 to alpha cell differentiation in developing pancreas. We hypothesized those transcription factors are important to produce specific hormones in pNETs, similarly to developing pancreas, and examined the expression of transcription factors in a case of MEN1 who showed immunohistological coexistence of several hormone-producing pNETs including insulinoma. A 70-year-old woman was found to manifest hypoglycemia with non-suppressed insulinemia and hypercalcemia with elevated PTH level. She was diagnosed as MEN1 based on the manifestation of primary hyperparathyroidism, pituitary adenoma and insulinoma, with genetic variation of MEN1 gene. She had pylorus-preserving pancreaticoduodenectomy because CT scan and SACI test indicated that insulinoma was localized in the head of the pancreas. Histopathological finding was MEN1-associated NET, G1. Interestingly, immunohistological examination of the resected pancreas revealed that two insulinomas, a glucagon-positive NET and a multiple hormone-positive NET coexisted. Hence, we examined the expression of transcription factors immunohistochemically to elucidate the role of the transcription factors in MEN1-associated hormone-producing pNETs. We observed homogeneous expressions of MafA and Pdx1 in insulinomas and Arx in glucagon-positive NET, respectively. Moreover, multiple hormone-positive NETs expressed several transcription factors heterogeneously. Collectively, our results suggested that transcription factors could play important roles in the production of specific hormones in MEN1-associated pNETs, similar to islet differentiation.

Learning points:

  • To date, it has been shown that different hormone-producing tumors coexist in MEN1-associated pNETs; however, the underlying mechanism of the hormone production in MEN1-associated pNETs has not been well elucidated.

  • Although this case presented symptomatic hypoglycemia, several hormone-producing pNETs other than insulinoma also coexisted in the pancreas.

  • Immunohistochemical analysis showed MafA and Pdx1 expressions distinctly in insulinoma, and Arx expression particularly in a glucagon-positive NET, while a multiple hormone-positive NET expressed MafA, Pdx1 and Arx.

  • Collectively, clinicians should consider that several hormone-producing pNETs may coexist in a MEN1 case and examine both endocrinological and histopathological analysis of pNETs, regardless of whether symptoms related to the excess of hormones are observed or not.

Open access

Etienne Larger, Nicolai J Wewer Albrechtsen, Lars H Hansen, Richard W Gelling, Jacqueline Capeau, Carolyn F Deacon, Ole D Madsen, Fumiatsu Yakushiji, Pierre De Meyts, Jens J Holst and Erica Nishimura

Summary

Glucagon stimulates hepatic glucose production by activating specific glucagon receptors in the liver, which in turn increase hepatic glycogenolysis as well as gluconeogenesis and ureagenesis from amino acids. Conversely, glucagon secretion is regulated by concentrations of glucose and amino acids. Disruption of glucagon signaling in rodents results in grossly elevated circulating glucagon levels but no hypoglycemia. Here, we describe a patient carrying a homozygous G to A substitution in the invariant AG dinucleotide found in a 3′ mRNA splice junction of the glucagon receptor gene. Loss of the splice site acceptor consensus sequence results in the deletion of 70 nucleotides encoded by exon 9, which introduces a frame shift and an early termination signal in the receptor mRNA sequence. The mutated receptor neither bound 125I-labeled glucagon nor induced cAMP production upon stimulation with up to 1 µM glucagon. Despite the mutation, the only obvious pathophysiological trait was hyperglucagonemia, hyperaminoacidemia and massive hyperplasia of the pancreatic α-cells assessed by histology. Our case supports the notion of a hepato–pancreatic feedback system, which upon disruption leads to hyperglucagonemia and α-cell hyperplasia, as well as elevated plasma amino acid levels. Together with the glucagon-induced hypoaminoacidemia in glucagonoma patients, our case supports recent suggestions that amino acids may provide the feedback link between the liver and the pancreatic α-cells.

Learning points:

  • Loss of function of the glucagon receptor may not necessarily lead to the dysregulation of glucose homeostasis.

  • Loss of function of the glucagon receptor causes hyperaminoacidemia, hyperglucagonemia and α-cell hyperplasia and sometimes other pancreatic abnormalities.

  • A hepato–pancreatic feedback regulation of the α-cells, possibly involving amino acids, may exist in humans.

Open access

Taiba Zornitzki, Hadara Rubinfeld, Lyudmila Lysyy, Tal Schiller, Véronique Raverot, Ilan Shimon and Hilla Knobler

Summary

Acromegaly due to ectopic GHRH secretion from a neuroendocrine tumor (NET) is rare and comprises <1% of all acromegaly cases. Herein we present a 57-year-old woman with clinical and biochemical features of acromegaly and a 6 cm pancreatic NET (pNET), secreting GHRH and calcitonin. Following surgical resection of the pancreatic tumor, IGF1, GH and calcitonin normalized, and the clinical features of acromegaly improved. In vitro studies confirmed that the tumor secreted large amounts of both GHRH and calcitonin, and incubation of pNET culture-derived conditioned media stimulated GH release from a cultured human pituitary adenoma. This is a unique case of pNET secreting both GHRH and calcitonin. The ability of the pNET-derived medium to stimulate in vitro GH release from a human pituitary-cell culture, combined with the clinical and hormonal remission following tumor resection, confirmed the ectopic source of acromegaly in this patient.

Learning points

  • Signs, symptoms and initial work-up of acromegaly due to ectopic GHRH secretion are similar to pituitary-dependent acromegaly. However, if no identifiable pituitary lesion is found, somatostatin receptor scan and further imaging (CT, MRI) should be performed.

  • Detection of GHRH in the blood and in the tumor-derived medium supports the diagnosis of ectopic GHRH secretion.

  • Functional bioactivity of pNET-secreted GHRH can be proved in vitro by releasing GH from human pituitary cells.

Open access

Shweta Birla, Viveka P Jyotsna, Rajiv Singla, Madhavi Tripathi and Arundhati Sharma

Summary

Multiple endocrine neoplasia type 1 (MEN-1) is a rare autosomal-dominant disease characterized by tumors in endocrine and/or non endocrine organs due to mutations in MEN1 encoding a nuclear scaffold protein‘menin’ involved in regulation of different cellular activities. We report a novel 14 bp MEN1 deletion mutation in a 35-year-old female with history of recurrent epigastric pain, vomiting, loose stools and weight loss. On evaluation she was diagnosed to have multifocal gastro-duodenal gastrinoma with paraduodenal lymph nodes and solitary liver metastasis. She was also found to have primary hyperparathyroidism with bilateral inferior parathyroid adenoma. Pancreatico-duodenectomy with truncalvagotomy was performed. Four months later, radiofrequency ablation (RFA) of segment 4 of the liver was done followed by three and a half parathyroidectomy. MEN1 screening was carried out for the patient and her family members. MEN-1 sequencing in the patient revealed a heterozygous 14 bp exon 8 deletion. Evaluation for pathogenicity and protein structure prediction showed that the mutation led to a frameshift thereby causing premature termination resulting in a truncated protein. To conclude, a novel pathogenic MEN1 deletion mutation affecting its function was identified in a patient with hyperparathyroidism and gastrinoma. The report highlights the clinical consequences of the novel mutation and its impact on the structure and function of the protein. It also provides evidence for co-existence of pancreatic and duodenal gastrinomas in MEN1 syndrome. MEN1 testing provides important clues regarding etiology and therefore should be essentially undertaken in asymptomatic first degree relatives who could be potential carriers of the disease.

Learning points

  • Identification of a novel pathogenic MEN1 deletion mutation.

  • MEN1 mutation screening in patients with pituitary, parathyroid and pancreatic tumors, and their first degree relatives gives important clues about the etiology.

  • Pancreatic and duodenal gastrinomas may co-exist simultaneously in MEN1 syndrome.

Open access

Avital Nahmias, Simona Grozinsky-Glasberg, Asher Salmon and David J Gross

Summary

Approximately 35% of the pancreatic neuroendocrine tumors (pNETs) are functional, the most common of which is an insulinoma. Rarely can initially nonfunctioning tumor undergo biological transformation to a hormone-secreting tumor with subsequent changes in the clinical picture. We present here three unique patients with long-standing pNETs who developed life-threatening hyperinsulinemic hypoglycemia along with tumor progression. In two of the patients, everolimus (Afinitor) was administered in an attempt to control both tumor growth and hypoglycemia. In two cases everolimus therapy resulted in the abolishment of hypoglycemia and induced significant tumor regression; however these beneficial responses were transient. These cases highlight the exceptional ability of pNETs to change biological behavior in parallel with disease progression. Our experience concurs with recently published studies demonstrating the utility of everolimus for the control of both hypoglycemia and tumor progression.

Learning points

  • Nonfunctional pNET can gain new features such as insulin secretion with related morbidity.

  • Gain of function in a previously nonfunctional pNET signifies tumor progression and is usually associated with poor prognosis.

  • Everolimus proved to be a viable treatment for hypoglycemia in insulinoma patients and was also proven highly effective in the patients presented here.

  • As disease progresses, the effect of everolimus on hypoglycemia wanes. We report for the first time the development of hypoglycemia during everolimus treatment.