Endocrine Abstracts

Introduction: Arginine vasopressin (AVP) disorder, formerly known as diabetes insipidus (DI), is a disease that results in either decreased release and/or secretion of antidiuretic hormone (AVP deficiency or central DI) or a reduced response to it (AVP resistance or nephrogenic DI). Carcinoid tumors are rare malignant neuroendocrine epithelial tumor, 25% occurring in the lungs, making them the second most common site. Atypical carcinoids and the development of metastases are associated with a poor prognosis.

Objectives and Methods: To present a case report of a 59-year-old female with AVP deficiency and panhypopituitarism caused by a metastatic neuroendocrine tumour, with cerebral and bone metastases.

Case presentation: In 2022 the patient presented with a mild polyuro-polydipsic syndrome (4 L/day of water intake and urinary output) and chronic fatigue for which she did a chest CT, revealing a 19 mm right inferior pulmonary lobe mass. Tumor biopsy showed an atypical neuroendocrine carcinoma, with a Ki-67 index of 40% and a positivity for chromogranin A, while the somatostatin receptors were negative. The FDG and DOTATOC scans showed secondary lesions in the mediastinal and inguinal lymph nodes, brain and sternum. The primary lesion was resected and she received chemotherapy and radiotherapy. One year later, she returned to the Emergency Department with increasing polyuro-polydipsic syndrome, with hypernatremia up to 147nmol/l and an episode of a seizure. The MRI showed a progression of the cerebral lesions, as well as a hypothalamic lesion of 9/6 mm compressing the pituitary stalk and she was referred to our clinic.

Results: The water intake and urinary excretion were up to 7 L/day, while the serum osmolality was normal (288 mOsm/kg) and urinary osmolality was at the normal inferior limit (81 mOsm/kg, normal range 50-1400). The blood tests showed panhypopituitarism and a mild hyperprolactinemia. Hydrocortisone, levothyroxine and desmopressin substitution treatments were started. The neurosurgical consultation concluded that the hypothalamic lesion was unresectable. Treatment consisted of systemic chemotherapy resumption and localized radiotherapy for the cerebral metastases. Furthermore, endocrine follow-up is required for hormonal treatment adjustment.

Conclusion: AVP deficiency and metastatic pulmonary neuroendocrine carcinoma are two of the rarest endocrine disorders which can greatly affect patients’ quality of life, the latter having a 5-year relative survival rate of 55%. Therefore, prompt diagnosis and treatment are mandatory, as well as close surveillance.