Metaplastic carcinoma of the breast and BRCA1 germline mutation: a case report and review

• Main Authors: Michiko Yamashita, Yoshiaki Kamei, Akari Murakami, Erina Ozaki, Kumiko Okujima, Kana Takemoto, Megumi Takaoka, Daiki Tsukamoto, Erina Kusakabe, Tomoyuki Shidahara, Haruna Noda, Reina Aoki, Kana Taguchi, Kanako Nishiyama, Mariko Eguchi, Yasutsugu Takada
• Format: Article
• Language: English
• Published: BMC 2021-01-01
• Series: Hereditary Cancer in Clinical Practice
• Subjects: Chondroid metaplasia; BRCA1 mutation; Triple-negative breast cancer
• Online Access: https://doi.org/10.1186/s13053-020-00162-x

Abstract Background Metaplastic carcinoma of the breast consists of both invasive ductal carcinoma and metaplastic carcinoma. This rare subtype of cancer has a poor prognosis. The development of metaplastic breast cancer and relationship with BRCA1 are not well known. Here, we report a rare case of germline BRCA1 mutation-positive breast cancer with chondroid metaplasia. Case presentation A 39-year-old Japanese woman with a family history of breast cancer in her mother and ovarian cancer in her maternal grandmother consulted at our hospital with a left breast mass. Needle biopsy for the mass was performed, leading to a diagnosis of invasive breast cancer with chondroid metaplasia. We performed left mastectomy + sentinel lymph node biopsy + tissue expander insertion and replaced with a silicone implant later. Pathological examination revealed that the patient had triple-negative breast cancer. Four courses of doxorubicin+ cyclophosphamide therapy were performed as adjuvant therapy after surgery. We performed genetic counseling and genetic testing, and the results suggested the germline BRCA1 mutation 307 T> A (L63*). She has currently lived without a relapse for 2 years post-surgery. Conclusions There have been only 6 cases of metaplastic breast carcinoma with germline BRCA1 mutations including our case. Patients with BRCA1 mutations may develop basal-like subtypes or M type of triple-negative breast cancer besides metaplastic breast cancers.