Pituitary Metastasis Presenting With Central Diabetes Insipidus and Panhypopituitarism

We report a case of pituitary metastasis (PM) presenting with acute anterior and posterior pituitary dysfunction following a two-decade-long oncologic course marked by disease progression.

An elderly woman with a history of stage IIA invasive ductal carcinoma of the breast presented with confusion. Her laboratory evaluation was significant for panhypopituitarism and central diabetes insipidus, and magnetic resonance imaging findings were suggestive of PM. She was treated with hormone replacement, resulting in the reversal of her metabolic and cognitive derangements.

PM is a rare complication of advanced malignancy. Although several malignancies may spread to the pituitary, the most common are breast cancer in women and lung cancer in men. Unlike pituitary adenomas, which predominantly involve the anterior pituitary, PM has a predilection for the posterior lobe and infundibulum due to direct access via systemic circulation. The clinical presentation of PM depends on the size of the metastatic deposit and other structures involved in the vicinity of the sella. Magnetic resonance imaging with gadolinium is the gold standard for the evaluation of sellar masses. The diagnosis of PM involves a thorough history, physical examination, biochemical evaluation of the hypothalamic-pituitary axis, and imaging studies.

Metastatic involvement of the pituitary is a rare condition seen in <2% of resected pituitary masses. The clinical presentation is heterogeneous and can include headache, visual impairment, and panhypopituitarism. Unfortunately, the presence of PM portends a poor prognosis, and the median survival rate after diagnosis is 6 to 13.6 months.