Severe Unresponsive Hypoglycemia Associated with Neuroendocrine Tumor of Unknown Primary Site - 18 Years after Rectal Cancer Surgery. Case Report.

INTRODUCTION: Neuroendocrine tumors are derived from cells that have the unique ability to synthesize, store and secrete a variety of metabolically active substances, peptides and amines, characteristic of the tissue of origin, which can cause distinct clinical syndromes.
MATERIAL AND METHODS: We present the case of a 58-year-old patient diagnosed and surgically treated in January 1996 for stage III inferior rectal cancer, who was readmitted after 18 years presenting persistent diarrheic syndrome and asthenia. Investigations performed (abdominal CT) showed multiple liver metastases, initially suspected as being related to the rectal cancer. Biopsy of liver metastases and pathological and immunohistochemical analysis demonstrated the neuroendocrine origin (moderately differentiated neuroendocrine tumor). Seven months after the identification of liver metastases and after initiation of oncological therapy with Interferon and Somatostatin, the patient presented severe hypoglycemia (serum glucose 13-70 mg/dl) proved to be due to insulin-like factors (serum insulin level 64.9 ìU/ml) secreted by metastases. Due to the aggressive evolution of neuroendocrine tumor, with multiple episodes of severe hypoglycemia, resistant to treatment, the patient died approximately one month after the occurrence of hypoglycemic episodes.
CONCLUSION: Despite comprehensive tests (abdominal CT scan, colonoscopy, bone scintigraphy and PET/CT), the primary site of the neuroendocrine tumors remained unknown.