# Case Report: A rare case of thyroid metastasis from breast cancer

## TL;DR

This case report describes a rare instance of breast cancer spreading to the thyroid and highlights the importance of considering this possibility in patients with a history of breast cancer.

## Contribution

The report adds to the limited literature on metastatic breast carcinoma to the thyroid and emphasizes the role of immunohistochemistry in diagnosis.

## Key findings

- MBCT presents with nonspecific symptoms and imaging findings.
- IHC analysis is crucial for distinguishing MBCT from primary thyroid cancer.
- Thyroidectomy with lymph node dissection can lead to stable outcomes in selected cases.

## Abstract

To analyze the clinicopathological features, diagnosis, and treatment strategies for metastatic breast carcinoma to the thyroid (MBCT) to enhance clinical awareness of this rare condition.

Analysis of clinical data from one MBCT patient and literature review.

A 41-year-old female with left breast invasive ductal carcinoma (IDC) received neoadjuvant AC-T chemotherapy, breast-conserving surgery, radiotherapy, and endocrine therapy. At eight years post-diagnosis, thyroid lesions were detected. Total thyroidectomy with lymph node dissection confirmed MBCT pathologically. No progression was observed at 16 months post-thyroidectomy.

MBCT is a rare clinical entity characterized by nonspecific clinical and radiological findings. Immunohistochemical (IHC) analysis is essential for a definitive diagnosis. In patients with a breast cancer history, MBCT should always be considered in the differential diagnosis of thyroid abnormalities.