Objective: To highlight awareness of the potential for breast carcinoma to manifest as a thyroid lesion.
Methods: We present two case reports of young women with thyroid nodules and discuss diagnostic techniques and treatment strategies.
Results: In two women, 32 and 38 years old, neither of whom had a history of carcinoma, thyroid nodules were suspected clinically of being primary thyroid neoplasms. In each case, histopathologic evaluation disclosed that the tumors appeared "foreign" to the thyroid and resembled infiltrating duct carcinomas of the breast. In some histologically confusing cases, immunostaining for thyroglobulin and calcitonin may prove diagnostically helpful. The usual treatment for lesions metastatic to the thyroid is surgical resection.
Conclusion: Metastatic breast carcinomas may manifest as primary thyroid lesions, especially in women younger than age 40 years.