Solitary pituitary metastasis from breast cancer masquerading as a pituitary macroadenoma: a report of 2 rare cases.

Background: Breast cancer is one of the most common malignant tumors, occurring in the mammary glands, which often metastasizes to bones, lungs, and liver. However, pituitary metastasis (PM) originating from breast cancer is a rare phenomenon that can easily be mistaken for benign pituitary macroadenoma. Case Description: This report details two cases of middle-aged and elderly Chinese women who presented with serious neurological symptoms, each with a history of breast malignancy. Both patients underwent magnetic resonance imaging (MRI), which showed a lesion in the sellar region, suggesting a pituitary adenoma. In one case, intraoperative frozen biopsy samples initially suggested a benign pituitary macroadenoma. However, post-surgical resection and permanent pathology combined with immunohistochemical stains confirmed both cases as symptomatic PM from breast cancer. Following surgery, one patient had a favorable postoperative prognosis, while the other unfortunately succumbed to systemic disease progression 5 months later. Conclusions: A history of a malignancy should raise the suspicion for metastatic disease in patients presenting with a lesion in the sellar region accompanied by symptoms. Due to its low incidence, diagnosing PM preoperatively is challenging. This case report aims to raise awareness among healthcare providers that this condition is crucial for timely and accurate diagnosis.