True or False: Leiomyosarcomas typically arise from leiomyomas.

Leiomyosarcomas and leiomyomas are both smooth muscle tumors but differ significantly in their nature and origin. Leiomyomas, also known as uterine fibroids, are benign tumors that arise from the smooth muscle layer of the uterus and typically do not transform into malignant tumors. Although leiomyomas can sometimes have atypical features or show abnormal characteristics, the vast majority retain their benign nature and do not progress to leiomyosarcoma.

On the other hand, leiomyosarcomas are malignant tumors of smooth muscle origin, which can appear de novo, meaning they can develop independently of pre-existing benign lesions. Therefore, the notion that leiomyosarcomas typically arise from leiomyomas is not accurate; while it’s possible for a benign tumor to acquire malignant features, this is exceptionally rare.

So, the assertion that leiomyosarcomas typically arise from leiomyomas is false, as the overwhelming evidence supports that they generally arise independently rather than from benign smooth muscle tumors.