Neuroendocrine Tumor with Clinical Characteristics of Insulinoma

J. Menezes; E. Rodrigues; C. Nogueira; C. Esteves; G. Jorge; M. Matos; L. Graca; J. Pinheiro; Loureiro Pinheiro; J. Lopes; J. Costa; Maia Costa; D. Carvalho

Introduction: Insulinomas are almost always located in the pancreas and are usually small. The peak incidence is from the third to fifth decade of life, with females being slightly more frequently affected. The average duration of neuroglycopenic symptoms prior to diagnosis is often prolonged, being more than 5 years in 20% of patients.

Case presentation: Female, 52 years old, medical history notable for hypertension, dislipidemia and Graves disease. She presented with a 4-month history of hypoglycemia with associated symptoms of weakness and tremor. The patient was admitted in the emergency room with garbled speech and disorientation. At that time, her finger-stick blood glucose level was 26 mg/dL. Because of the suspicion of insulinoma, a complete endocrine evaluation was performed specifically, the patient was observed while fasting. At 26 hours of fasting the blood glucose level was of 43 mg/dL, with response to glucagon injection, and the patient was found to have insulin level s >3 UI/mL and C-Peptide value >=0.6 ng/mL, with glycemia <55 mg/dL. Parathyroid hormone and calcium were normal. A high-resolution CT demonstrated a heterogeneous enhancing mass 2.9 cm. The patient was submitted to laparoscopic distal pancreatectomy. A a neuroendocrine well differentiated tumor (2.8×1.7×0.9 cm) – G1 (ENET) – pT2N0R0 was found in the tail of the pancreas. Immunohistochemical stains for chromogranin and synaptofisin were positive, however for insulin was negative. Less than 2% of the tumor cells were ki67+. Postoperativelty, the patient’s symptoms resolved with no further hypoglycemic events.

Conclusion: We report this case because it took just 4 months for diagnosis, because of the dimensions of the tumor and also because, although the biochemical diagnosis of insulinoma was established, there was no immunohistochemical evidence of insulin production. The patient glycemia however returned to normality with no further symptoms.

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This research did not receive any specific grant from any funding agency in the public, commercial or not-for-profit sector.

Endocrine Abstracts

P799