A smooth muscle tumor is a type of growth that arises from smooth muscle cells, which are found in various organs such as the uterus, stomach, and blood vessels. These tumors can be benign, meaning they are not cancerous, or malignant, which means they can spread to other parts of the body. The most common benign smooth muscle tumor is called a leiomyoma, often found in the uterus. Diagnosis typically involves imaging tests like ultrasound or MRI, and sometimes a biopsy is performed to confirm the type of tumor. Treatment options may include monitoring, surgical removal, or medication, depending on the tumor's size, location, and whether it is benign or malignant.