A rare incidental case of an occult breast carcinoma micrometastasis in papillary thyroid carcinoma: A view within a view

Metastasis to thyroid gland is rare, accounting for only 2%–3% of malignant lesions of thyroid and if present, is associated with a poor prognosis. Herein, we describe a case of a 42-year-old female who presented initially with papillary carcinoma of the thyroid and a synchronous malignancy was pointed toward on the basis of a secondary population of atypical cells in intrathyroidal as well as perithyroidal blood vessels emboli. Immunohistochemistry and systematic review of the patient later proved the micrometastasis to be that of carcinoma breast for which the patient was operated 6 years ago. The present case is worth reporting because it documents the presence of two different cancers in a single-organ system (a rare presentation of breast ductal cancer metastasizing to the papillary thyroid carcinoma) by the means of an important yet overlooked lymphovascular compartment, by the identification of the metastatic tumor emboli.