Yes, they are usually non malignant as i have stated before(they are benign) It is also said in the scientific studies that I provided you.

I said before that the polyps often derive from fibroid tissue, polyps have been found on fibroid tissue. They are attached to eachother and are also treated the same way. Both are outgrowth "benign tumor", and often referred to as "fibroids". Uterine fibroids are common benign growths that develop in the muscular wall of the uterus and are usually removed (with hysterectomy).

"The prominent dendriform central fibrous core on MRI reflected a thick stalk originating from the myometrium with numerous branches containing abundant smooth muscle fibers, and may represent the pathologic feature of adenomyomatous polyp." -This is from here.

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