Which tumor is characterized as benign and made up of muscle tissue?

The term "myoma" refers specifically to a benign tumor composed of muscle tissue. These tumors can arise from smooth muscle, as in the case of uterine fibroids (leiomyomas), or striated muscle. Myomas are generally well-circumscribed, grow slowly, and do not invade surrounding tissues, which is indicative of their benign nature.

In contrast, other tumors listed, while also associated with specific tissues, carry different characteristics. For example, malignant fibrous histiocytoma is actually a malignant tumor that arises from fibrous tissue, indicating it is not benign like a myoma. Fibromas are benign tumors but are made of fibrous tissue, not muscle. Lipomas, while benign as well, are composed of adipose (fat) tissue. Thus, myoma is distinct in its classification as a benign muscle tumor.