I have a thigh lump, over the muscle. it is 2.5x1.5cm although it looks much bigger. mri and dopler shoes uncapsulised lypoma. to be 100% sure, doc still requests biopsy. are there any chances biopsy to turn benign into malign tissue?

An MRI is quite accurate in diagnosing simple lipomas. However, if there's any concern that the lipoma has any atypical features, a biopsy is usually performed to rule out a liposarcoma.

No. Biopsy will turn a benign tumor into a malignant one. You can reduce your risk of cancer by adopting healthy habits: Eat a mostly vegetarian diet, avoid alcohol, tobacco and street drugs, avoid excessive exposure to sun, maintain healthy weight, get HPV vaccine, exercise 30 minutes each day, drink enough water so your urine is mostly colorless. Wish you good health!

The entire mass should be removed and then will be biopsied. The act of biopsy does not convert tissue to malignancy