CASE REPORT article
Front. Oncol.
Sec. Genitourinary Oncology
This article is part of the Research TopicExploring the Breast Tumor Microenvironment: Association to Metastasis, Novel Risk Factors and Novel Treatments and Immunotherapies: Volume II.View all 15 articles
Breast Cancer Occult in Renal Cell Carcinoma: A Case Report of a Rare Tumor-to-Tumor Metastasis and Literature Review
Provisionally accepted
- 1The First people's Hospital of Xiaoshan District, Hangzhou, China
- 2Shanghai First Materity and Infant Hospital, Shanghai, China
- 3The Second People's Hospital of Xiaoshan District, Xiaoshan District, Hang zhou, China
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Metastasis from breast cancer (BC) to renal cell carcinoma (RCC) is rare. We retrospectively analyzed the clinical data, i.e., medical history, imaging, and laboratory examinations, as well as pathological features of a 62-year-old female with invasive ductal carcinoma of the breast metastasizing to clear cell renal cell carcinoma (CCRCC). A comprehensive literature review was also conducted. Her right breast mass was pathologically diagnosed as invasive ductal carcinoma eight months ago. A large mass in the left kidney was incidentally discovered during a computed tomography (CT) scan, which was consistent with RCC. She underwent neoadjuvant chemotherapy, radical mastectomy, and endocrine therapy, as well as laparoscopic left nephrectomy four months postoperatively. Her pathological examination revealed two heterogeneous tumor components in the kidney: typical CCRCC [CD10+, Vimentin+, carbonic anhydrase Ⅸ (CAIX)+, paired box gene 8 (PAX-8)+, 3% Ki-67 proliferation index) as well as multifocal metastatic invasive ductal carcinoma of the breast (estrogen receptor (ER) 50%+++, GATA binding protein 3 (GATA3) +, Human epidermal growth factor receptor-2 (HER-2) 1+, and 20% Ki-67 proliferation index). These findings met the diagnostic criteria for TTM. She also continued BC endocrine therapy postoperatively. However, no recurrence or metastasis was observed during the 11 follow-up months.
Keywords: breast cancer, Clear cell renal cell carcinoma, Immunohistochemistry, metastasis, Pathological diagnosis, Tumor-to-tumor
Received: 24 Sep 2025; Accepted: 02 Dec 2025.
Copyright: © 2025 Huang, Han, Zhang and Liu. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence:
Yanjie Zhang
Hongsheng Liu
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