An interesting case of likely BRCA2 related bilateral breast cancer with metastasis in the fimbrial part of fallopian tube

BACKGROUND: In a patient with a germline BRCA2 pathogenic variant with breast cancer, an adnexal mass can represent either a metachronous primary tumor or a metastasis of the breast cancer. A clear distinction between those two possibilities is crucial since treatments differ substantially and so does survival of the patient. CASE PRESENTATION: We present a case of a 47-year-old patient with bilateral breast carcinoma with a germline BRCA2 pathogenic variant. The first manifestation of the disease was a lump in her left breast in 1998, histological report was invasive ductal carcinoma, triple-negative. She was treated with surgery, chemotherapy and radiotherapy. In 2011 a new occult carcinoma was found in her right axilla, however the specimen was estrogen receptor (ER) and progesterone receptor (PgR) positive. She was treated as a new primary occult carcinoma of the right breast with surgery, radiotherapy and adjuvant hormonal treatment. In 2016 a mass in the left adnexa was found with imaging techniques. She underwent surgery as if it was primary ovarian cancer, yet histology revealed it was a metastasis of a triple-negative breast carcinoma in the fimbrial part of the left Fallopian tube. She received adjuvant chemotherapy after surgery and is now in complete remission. CONCLUSION: We present an interesting and quite rare case of two primary breast carcinomas in a patient with a known BRCA2 pathogenic variant with metastasis in the fimbrial part of the left Fallopian tube. We conclude that there were two primary breast tumours and the one from 2011 spread into the fimbrial part of the left Fallopian tube in 2016. Despite the fact that molecular analyses could not confirm the joint tumour origin, we believe that there was a receptor status conversion over time explaining different receptor status. The possibility of a triple-negative metastasis from the tumour treated in 1998 is less probable. With both of aforementioned possibilities being prognostically unfavourable, the patients’ outcome is so far excellent and she was in complete remission at the time of writing this article.