Giant Renal Metastasis as a Late Recurrence of Hormone Receptor-Positive Breast Cancer with Synchronous Brain Metastases: A Case Report

Abstract

Author(s): K. Soussy1,2,3*, M. Chrifi Alaoui1,2,3, W. Hassani1,2,3, FZ. Farhane1,2,3, Z. Alami1,2,3, T. Bouhafa1,2,3

Renal metastases from breast cancer are uncommon and may mimic a primary renal malignancy. We report the case of a 60-year-old woman with a history of hormone receptor-positive, HER2-negative breast cancer treated with mastectomy, adjuvant chemotherapy, radiotherapy, and 5 years of endocrine therapy. Seven years after the initial diagnosis and approximately two years after completion of endocrine therapy, she developed progressive left lumbar pain and focal seizures involving the right upper limb. Imaging revealed a giant left renal mass measuring 18.2 cm and three brain lesions. Because the renal lesion was initially suggestive of a primary renal tumour, a percutaneous biopsy was performed. Histology showed an undifferentiated carcinoma with strong diffuse oestrogen receptor expression, progesterone receptor negativity, and HER2 score 0, supporting metastatic breast carcinoma. The three brain metastases were treated with stereotactic radiotherapy at a dose of 35 Gy in five fractions. The renal lesion was considered unresectable because of its size and vascular involvement. Systemic treatment with fulvestrant and ribociclib was initiated, with stable disease at the first assessment. This case highlights the importance of tissue diagnosis when an unusual renal mass develops in a patient with a history of breast cancer, even after a prolonged disease-free interval.

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