Medullary Thyroid Carcinoma Presenting as Metastatic Disease to the Breast

Abstract EN

Medullary thyroid carcinoma (MTC) is a neuroendocrine tumor that is derived from C cells of the thyroid gland.

It is a rare aggressive tumor, known to metastasize to lymph nodes, liver, bones, and lungs.

A 41-year-old female, who presented with a breast mass, was initially diagnosed with invasive ductal carcinoma.

She was also found to have a thyroid mass which was later diagnosed as MTC.

On a rereview of the breast pathology, the morphologic features were strikingly similar to the MTC.

Further investigation revealed that this was in fact a very rare case of MTC that had metastasized to the breast.

We have identified 20 cases of MTC metastasizing to the breast in the literature that supports its occurrence as a real possibility.

Albeit rare, medullary thyroid carcinoma should be considered in the differential diagnosis of a breast mass.