Islet cell hyperplasia of the pancreas presenting as hyperinsulinemic hypoglycemia in an adult

Diffuse, Adult-Onset Nesidioblastosis/Non-Insulinoma Pancreatogenous Hypoglycemia Syndrome (NIPHS): Review of the Literature of a Rare Cause of Hyperinsulinemic Hypoglycemia

Differential diagnosis of hypoglycemia in the non-diabetic adult patient is complex and comprises various diseases, including endogenous hyperinsulinism caused by functional β-cell disorders. The latter is also designated as nesidioblastosis or non-insulinoma pancreatogenous hypoglycemia syndrome (NIPHS). Clinically, this rare disease presents with unspecific adrenergic and neuroglycopenic symptoms and is, therefore, often overlooked. A combination of careful clinical assessment, oral glucose tolerance testing, 72 h fasting, sectional and functional imaging, and invasive insulin measurements can lead to the correct diagnosis. Due to a lack of a pathophysiological understanding of the condition, conservative treatment options are limited and mostly ineffective. Therefore, nearly all patients currently undergo surgical resection of parts or the entire pancreas. Consequently, apart from faster diagnosis, more elaborate and less invasive treatment options are needed to relieve the patients from the dangerous and devastating symptoms. Based on a case of a 23-year-old man presenting with this disease in our department, we performed an extensive review of the medical literature dealing with this condition and herein presented a comprehensive discussion of this interesting disease, including all aspects from epidemiology to therapy.

Nesidioblastosis. A case of hyperplasia of the islets of Langerhans in the adult

INTRODUCTION

Nesidioblastosis is a rare disease caused by hyperplasia of pancreatic islets, developing a state of hypoglycemia due to an increase in the insulin production. It is the leading cause of hyperinsulinic hypoglycemia in childhood, whereas in adults it only represents the 0.5-5% of cases. The pathogenesis is still unknown. We have studied several genetic mutations associated with dependent potassium channel of ATP present in the beta cells of the pancreas, as well as in patients underwent bariatric surgery because of the metabolic changes involved.

REPORT

Woman (38 years old) attends consultation of General Surgery derived from Endocrinology before symptoms of persistent hypoglycemia. Factitious hypoglycemia and syndromes of neuroendocrine origin were ruled out. Imaging tests failed to identify space-occupying lesions. The medical treatment failed, persisting hypoglycemia symptoms. Before the given analytical and radiological findings obtained, and the persistence of symptoms affecting the quality of life of the patient, we opted for surgical treatment performing a pancreatectomy of the 80% of the gland. The final pathologic diagnosis was nesidioblastosis.

DISCUSSION

Nesidioblastosis is a rare pathology, but it must be present in the differential diagnosis of hypoglycemia symptoms with endogenous hyperinsulinism in adults, once the intake of sulfonylureas and possible pancreatic neoformations have been ruled out.

Pathologic pancreatic endocrine cell hyperplasia

Pathologic hyperplasia of various pancreatic endocrine cells is rare but has been long known. β cell hyperplasia contributes to persistent hyperinsulinemic hypoglycemia of infancy, which is commonly caused by mutations in the islet ATP-sensitive potassium channel, and to non-insulinoma pancreatogenous hypoglycemia in adults, which may or may not be associated with bariatric surgery. α cell hyperplasia may cause glucagonoma syndrome or induce pancreatic neuroendocrine tumors. An inactivating mutation of the glucagon receptor causes α cell hyperplasia and asymptomatic hyperglucagonemia. Pancreatic polypeptide cell hyperplasia has been described without a clearly-characterized clinical syndrome and hyperplasia of other endocrine cells inside the pancreas has not been reported to our knowledge. Based on morphological evidence, the main pathogenetic mechanism for pancreatic endocrine cell hyperplasia is increased endocrine cell neogenesis from exocrine ductal epithelium. Pancreatic endocrine cell hyperplasia should be considered in the diagnosis and management of hypoglycemia, elevated islet hormone levels, and pancreatic neuroendocrine tumors. Further studies of pathologic pancreatic endocrine cell hyperplasia will likely yield insights into the pathogenesis and treatment of diabetes and pancreatic neuroendocrine tumors.

Surgical experiences of functioning neuroendocrine neoplasm of the pancreas

We present our surgical experiences with functioning neuroendocrine neoplasms of the pancreas to define its natural history, and to suggest its proper management. From June 1990 to June 2005, patients with diagnosis of functioning neuroendocrine (islet cell) neoplasms of the pancreas were retrospectively reviewed. Fourteen patients (5 men and 9 women) with a median age of 49 years (range, 12 - 68 years) were identified. Twelve patients (86%) had insulinoma, two (14%) had gastrinoma. One (7%) with pancreatic insulinoma was multiple endocrine neoplasia type 1. Intraoperative ultrasound scan (sensitivity, 83%) was the most powerful modality for tumor localization. Fifteen neoplasms with median tumor size 1 cm (range 0-3 cm) were resected. Four insulinomas (26.7%) were located in the head of the pancreas and 5 (36%), in the tail. Another 5 (36%) insulinomas and 1 (7%) gastrinoma were located around the neck area near the SMV or PV. Eleven patients (79%) underwent enucleation, and 2 patients (14%), distal pancreatectomy with splenectomy. 100% of patients with functioning neuroendocrine neoplasms of the pancreas have survived. The overall disease free 10-year survival was found to be about 81%. Exact localization of tumor by intraoperative ultrasound and surgical removal are promising for good prognosis.