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

Abstract

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.

Keywords: Breast cancer; case report; pituitary adenoma; pituitary metastasis (PM).

Figure 1

MRI with a slice thickness of 2 mm and a field strength of 3.0 T, demonstrating a sellar mass that is compressing the right internal carotid artery and optic chiasm, as well as invading the cavernous sinus. (A) Coronal T1-weighted gadolinium-enhanced scan, (B) sagittal T1-weighted gadolinium-enhanced scan, (C) axial T2-weighted scan (arrows: sellar lesion). L, left; R, right; A, anterior; P, posterior; MRI, magnetic resonance imaging.

Figure 2

Histopathological and immunohistochemical findings of the removed tumor. (A,B) HE staining shows glandular structures composed of enlarged, hyperchromatic cells with interstitial reaction. Immunohistochemical staining shows (C) HER2 (1+), (D) GATA3 (+), (E) ER (3+, 90%), and (F) PR (1+, 10%). HE, hematoxylin and eosin; HER2, human epidermal growth factor receptor 2; GATA3, GATA binding factor 3; ER, estrogen receptor; PR, progesterone receptor.

Figure 3

MRI with a slice thickness of 2.5 mm and a field strength of 3.0 T, demonstrating a sellar mass causing compression of the pituitary stalk and optic chiasm. (A) Coronal T1-weighted gadolinium-enhanced scan, (B) sagittal T1-weighted non-enhanced scan, (C) coronal T2-weighted scan (arrows: sellar lesion). R, right; A, anterior; P, posterior; L, left; MRI, magnetic resonance imaging.

Figure 4

Histopathological and immunohistochemical findings of the removed tumor. (A,B) HE staining shows solid structure composed of enlarged, hyperchromatic cells. Immunohistochemical staining shows (C) HER2 (0), (D) GATA3 (+), (E) ER (2+, 75%), and (F) PR (1+, 5%). HE, hematoxylin and eosin; HER2, human epidermal growth factor receptor 2; GATA3, GATA binding factor 3; ER, estrogen receptor; PR, progesterone receptor.