Diabetes insipidus and breast cancer.

Diabetes insipidus, resulting from metastatic involvement of the neurohypophysial system, is a rare complication of breast cancer. This review examined the clinical features, metastatic pattern, and radiological and postmortem findings of 39 breast cancer patients with this complication. All patients had polyuria and polydipsia, and all had evidence of advanced metastatic breast cancer. A high incidence of meningeal carcinoma carcinomatosis and/or sellar metastases was observed. In view of the anatomical proximity of the posterior pituitary to the dura mater and the sella turcica, our findings suggest that metastases to the neurohypophysis can occur not only as a result of hematogenous dissemination of malignant cells, but also from direct tumor extension and/or invasion from adjacent structures. Although satisfactory symptomatic relief can be obtained with vasopressin tannate, complete resolution of the diabetic insipidus syndrome was evident only in those patients who had achieved control of the underlying breast disease.