A Collision Tumor Involving a Primary Leiomyosarcoma of the Lower Extremity and a Metastatic Medullary Thyroid Carcinoma: A Case Report.

A wide diagnostic differential and thorough histologic analysis are necessary in patients presenting with neoplasms of the extremities. A leiomyosarcoma may be a hospitable location for metastatic disease, and the presence of a collision tumor should be considered when pathology findings are equivocal.