I have 3.1cm growth in glute. After ultrasound docfound cystic and solid component that could be atypical lipoma or hematoma. Could this be sarcoma?

Unlikely. While it is possible, it is very unlikely. Options include repeat imaging in 3-6 months, or surgical removal. Ask your doctor what is best for you. It's important to realize however that nobody can see the future, and any test can be incorrect. Go with your gut feeling after a thoughtful discussion with your doc. Hope this helps!