RESUMEN
BACKGROUND: Thyroid metastasis arising from primary breast cancer is a rare phenomenon, with only a handful of cases documented in both national and international literature. The management approach and prognosis of this occurrence have sparked debates and uncertainties. CASE PRESENTATION: Herein, we report the case of a 55-year-old woman with breast cancer. She previously underwent extensive excision of the breast lesion with adjuvant chemotherapy and endocrine therapy. After 9 years, she presented with neck discomfort and examination suggested right thyroid metastasis and lymph node metastasis in the neck. Imaging showed pulmonary and bone metastases. Furthermore, the patient received endocrine therapy. After 7 months of follow- up, the patient survived without any new distant metastases. Thyroid metastases originating from breast cancer often unfold with a subtle, intricate nature, making early detection challenging. They tend to emerge inconspicuously, intertwining with widespread systemic metastases, hinting at a less favorable prognosis. CONCLUSION: Given the unusual clinical indicators, identifying heterochronic thyroid metastases in patients with tumors poses a distinct challenge, requiring clinicians to navigate the follow-up process with heightened sensitivity. The key lies in timely detection and early intervention, factors that can significantly enhance the overall quality of life for patients.