[Metastasis from breast cancer to the pituitary gland causing hyponatriaemia]

Breast cancer is the most common cancer in Danish women. Pituitary metastases are rare events. We report a 75-year-old woman with metastatic breast cancer who presented with pituitary insufficiency nine years after her initial cancer diagnosis. MRI of the pituitary region showed a parasellar mass and thickening of the infundibulum. Her condition progressed within months and deterioration of visual field and acuity developed. A transsphenoidal resection was performed to rescue her vision and pathology confirmed metastasis from a breast invasive ductal adenocarcinoma.