Solitary Pituitary Metastasis of Advanced Breast Cancer Treated with Anti-Human Epidermal Growth Factor Receptor 2 Drug

ABSTRACT

Metastasis to the pituitary gland from systemic cancer is a rare condition. The breast and lung are the most common sites of primary tumor metastasis. Most often, they occur in the setting of widespread metastatic disease, which most frequently occurs in elderly patients. However, an increase in the incidence of solitary pituitary metastasis of breast cancer as the first recurrence has been reported. Diabetes insipidus is the most frequent symptom at presentation, and visual field defects or cranial nerve deficits are common symptoms of pituitary metastasis. Unlikely these symptoms, deficiencies of anterior pituitary hormones may only become evident in critical situation because symptoms are of an insidious onset and sometimes nonspecific. We report here on a rare case of solitary pituitary metastasis from breast cancer presenting as hyponatremia without other symptoms.