Primary leiomyosarcoma of the thyroid with concurrent papillary thyroid cancer: a rare case report and a review of literature.

Background: Leiomyosarcoma (LMS) is a soft tissue malignant tumor that has a predilection to the abdominopelvic and limb smooth muscles. LMS of the thyroid is exceptionally rare. Papillary thyroid cancer (PTC) is the most common thyroid malignancy and originates from the thyroid epithelial layer.