A Rare Presentation of Metastatic Breast Carcinoma to the Thyroid Three Years after Mastectomy: A Case Report

Abstract

Abstract Introduction: Breast cancer is the most common cancer in women. Yet, metastasis to the thyroid is a rare occurrence. Here we present the case of a patient with breast cancer metastasis to the thyroid gland to discuss the management of such presentations compared to the current literature. We also present this case to add to the existing literature and aid in the expansion and better understanding of rare incidences as such. Presentation of Case: A 38-year-old female with no chronic medical illnesses was diagnosed with invasive ductal carcinoma of the right breast T3N0M0 in 2017. Chemotherapy eight cycles of neoadjuvant chemotherapy followed by right simple mastectomy, sentinel lymph node biopsy, and adjuvant radiation to the chest wall. The patient has been on hormonal therapy since diagnosis. In 2020, the patient presented with a left neck mass and underwent a total thyroidectomy. Pathological analysis of the specimen confi rmed the presence of poorly differentiated cells consistent with mammary ductal cells while the right thyroid lobe demonstrated features of papillary thyroid carcinoma. Conclusion: Intrathyroidal metastasis of extrathyroidal cancers is rare but should be considered when patients are present with a history of cancer. Thyroidectomies in isolated secondary thyroid cancers have been shown to prolong the disease-free period but are not a defi nitive cure