Breast cancer metastasis to the sellar region: a case report and literature review

Pituitary metastasis (PM) is a rare but clinically significant entity, accounting for approximately 1–4% of surgically resected sellar lesions. Its presentation often mimics that of benign pituitary adenomas, making preoperative diagnosis challenging. Breast cancer is among the most common primary sources of PM, yet the long disease-free interval in some cases can obscure the suspicion of metastatic disease. This article delineates a paradigmatic case of a 73-year-old female with a history of invasive ductal breast carcinoma who developed a symptomatic sellar mass, the preoperative differential diagnosis of which included a non-functioning pituitary adenoma, meningioma, Craniopharyngioma, Rathke’s cyst, or metastatic lesion. The patient underwent transcranial resection, with definitive histopathological and immunohistochemical analysis confirming metastatic breast carcinoma. Histopathological and immunohistochemical analysis of the resected specimen revealed metastatic breast carcinoma with strong ER positivity (90%), PR positivity (25%), negative HER2, and a Ki-67 proliferation index of 40%. Negative staining for synaptophysin excluded a neuroendocrine origin. Gross total resection was achieved, and the patient’s vision stabilized postoperatively. However, anterior pituitary function declined, requiring hormone replacement. She was referred for systemic endocrine therapy, but experienced rapid systemic disease progression and died three months after surgery. This case underscores that pituitary metastasis should remain in the differential diagnosis of any sellar mass in patients with a history of breast cancer, even after a decade of disease-free survival and in the absence of classic signs such as diabetes insipidus. A high index of suspicion, timely histopathological confirmation, and multidisciplinary management are essential for optimizing patient care.