Breast Metastasis from Medullary Thyroid Carcinoma in a Male Patient: Case Report and Review of the Literature.

Medullary thyroid carcinoma (MTC) is a rare malignancy that may metastasize to liver, lungs and bones. Breast is an unusual metastatic site for MTC and only 20 female cases have been reported in the literature. We present a male patient in whom histological examination and immunohistochemistry of a breast mass were indicative of breast metastasis from MTC. A 67-year-old man with recent diagnosis of MTC and metastases to cervical and upper mediastinum lymph nodes was referred to our department for further treatment. At first evaluation, diagnostic imaging techniques showed lung and bone metastases and three months later the presence of liver metastases. Due to the extension of the disease, treatment with vandetanib was decided, but serious adverse events led to its interruption after two weeks. During follow-up, patient developed a painful swelling in the right breast. Ultrasound and mammography showed the presence of multiple masses to the right breast suspicious for malignancy. Core needle biopsy and histological examination of the specimen confirmed the presence of metastatic MTC. Palliative external beam irradiation was used to relieve local pain and, after one month, the patient died. Consequently, breast masses should be cautiously evaluated, mainly in the presence of a known primary malignancy. Histological and/or cytopathological examination are requisite diagnostic tools, while external beam irradiation and tyrosine kinase inhibitors may be used as palliative therapies in the concurrent presence of breast metastases from MTC.