A solitary brain metastasis as the only site of recurrence of HR positive, HER2 negative breast cancer: a case report and review of the literature

BACKGROUND: Breast cancer is one of the most common causes of brain metastases. However, the presence of isolated central nervous system (CNS) metastatic disease early in the course of disease relapse is a rare event in cases of hormone receptor positive, human epidermal growth factor receptor 2 (HER2) negative breast cancer. CASE PRESENTATION: We summarize the clinical course of a pre-menopausal, 39-year old Caucasian female with history of operable, hormone receptor positive, HER2 negative breast cancer who was initially treated with curative-intend therapy but who unfortunately developed solitary metastatic lesion in the left thalamus. A biopsy of the lesion confirmed the presence of hormone receptor positive, HER2 negative metastatic breast cancer. Patient’s CNS metastases continued to progress without any evidence of metastatic disease outside of the central nervous system and she eventually passed away about 5 years after the date of her initial diagnosis and 18 months following the diagnosis with brain metastasis. CONCLUSION: Based on our case, although rare, patients with treated, operable, hormone receptor positive, HER2 negative breast cancer can present with solitary brain metastasis as the only sign of disease recurrence.