Breast metastasis in follicular thyroid cancer patient

In this case report, we aimed to present the findings of a follicular thyroid carcinoma patient with breast metastasis, which is rarely reported in the literature. A 33-year-old female who had been operated for thyroid cancer 17 years ago, but whose pathology report could not be reached was suspected of recurrence in the left lobe region of the thyroid gland. Fine-needle aspiration biopsy was done in this region, and the biopsy result was reported as thyroid follicular carcinoma. ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) was performed for re-staging before surgery. In the PET/CT, it was found that there was residual thyroid tissue in the right and left lobe region and superior to these lesions in the left side, there were lesions which destruct to the hyoid bone, and there were multiple nodular lesions in both lungs which measured with maximum 15 mm × 12 mm, and all these lesions have increased ¹⁸F-FDG uptake. In addition to these lesions, a nodular lesion with the size of ~11 mm ×10 mm in the upper-middle quadrant of the right breast, and it was showing increased ¹⁸F-FDG uptake (maximum standardized uptake value: 3). Pathology results of the left neck region operation materials were reported as papillary and follicular carcinoma of the thyroid gland. Right lumpectomy was performed for the lesion in the right breast during the same session with thyroid operation. The pathology result of this lesion was also reported as metastasis of thyroid follicular cancer. Posttreatment iodine-131 whole-body scan after surgery was reported as there was abnormal accumulation in residual thyroid tissues on the right side of the neck and lung metastases. In patients with thyroid cancer, the possibility of metastasis of the breasts should be considered when there is a lesion in the breast tissue.