Occult Follicular Thyroid Carcinoma presenting as Primary Breast Tumor with Sternal and Skull Metastasis

Abstract

Introduction: Follicular thyroid carcinoma (FTC) that initially presented as breast tumor with no previous medical history of malignancy of thyroid gland is relatively rare and may cause diagnostic confusion.

Presentation of case: We report a 59-year-old Mexican woman with no prior history of malignant thyroid neoplasm that presents with pain and swelling in the upper outer quadrant of the left breast with a year of evolution. Subsequently, subcutaneous tumor was identified in left parietal region. Clinically it was thought in primary breast tumor metastasis to skull. Furthermore, computerized tomography scan identified a tumor in the deep portion of the left breast, infiltrating the sternum that subsequently was confirmed a follicular carcinoma of the thyroid gland.

Conclusion: Metastatic FTC may mimic a primary breast tumor. The combined use of clinical information, histopathology and immunohistochemistry were important to establishing a correct cancer diagnosis.