Primary Malignant Fibrous Histiocytoma of the Thyroid: Two Case Reports and Review of the Literature.

Primary malignant fibrous histiocytoma of the thyroid is an uncommon malignancy of the thyroid. Because it is rare, fewer than 20 cases have been reported in the literature, and the sonographic features of only 2 cases have been reported between the 1980s and 2014. Here we report 2 cases of primary malignant fibrous histiocytoma of the thyroid with an emphasis on the sonographic findings, and we review the published literature.