Case Report: Collision Tumour of Colon Leiomyosarcoma and Adenocarcinoma.

The colon is an exceedingly rare site of primary leiomyosarcoma and only a few cases have been published to date. Of the reported cases of collision tumours, collision tumours that specifically occurred in the colon have consisted of combinations of adenoma or adenocarcinoma with lymphomas or neuroendocrine tumours. Here, not only do we report a case of colon leiomyosarcoma, but we report, what is to our knowledge, the first case of collision tumour consisting of colon leiomyosarcoma and adenocarcinoma. Cause, prognosis, and treatment of colon collision tumours vary and are yet to be understood.