Do you have any advice for a very painful and hard intramuscular lipoma in lower back?

Thank you for sharing your question and I am sorry to hear of your continued lower back pain.  I would advocate seeking second opinions regarding the mass, its diagnosis, and possible treatment options.  The symptoms you describe are not typical for a lipoma and other considerations need to be ruled out for safety purposes.  Hope this helps.

This is a malignancy until proven otherwise. Lipomas do not grow fast, they are not hard and painful, and intramuscular, subfascial masses, even if they are lipomas are more associated with malignancy, like liposarcoma or other mesenchymal sarcomas. Lipomas are soft,  mobile, and when subcutaneous, the MRI virtually always confirms benign lipoma.  You should NOT "live with it".  Evaluation of these kinds of tumors, needs immediate MRI, and no one should touch it or put a needle into it other than  your regional  orthopedic oncology  referral  center.  Go to the unit in Ghent. While history and physical exam and MRI may point to a diagnosis other than a soft tissue sarcoma, without an MRI and expert evaluation, you have no way of knowing and do not delay.   See article re work up and delay.LoDeGr Belgium, BEHello! I'm a 22 year old female, in decent shape, otherwise healthy. Strange lump (hard and painful), became more and more painful in 2 months' time - walking, coughing. A picture & diagnosis: intramuscular lipoma, a "hypo-echogenic nodus of 2.3 on 2.7 cm, homogenous", on the "source?" of the gluteus maximus, left side lower back. No further research, operation apparently no option. Pain keeps getting worse and back feels tight and tense in its vicinity. Doctor says I should simply try to live with it. I am not sure what to do, do you have any advice

You should get this further evaluated. Probably an MRI scan would be advisable. The features you describe are not typically for a lipoma. Other possibilities include a hernia, a benign tumour e.g. schwannoma, or a malignant tumour. Malignant tumours in this area are rare, when they occur they are usually sarcomas. Lipomas can be hard and painful but it is very unusual. If a lipoma is tender then removing it frequently helps the pain.You should also consider the possibility that the pain is not coming from the lump. I not infrequently see patients with lipomas and pain and the pain is not from the lipoma. Often it is coming from the spine or neck.You should see a specialist with knowledge in the diagnosis of soft tissue tumours. Such specialists may come from differing specialties such orthopaedics, general surgery or plastic surgery. The specialty does not matter clinical experience in soft tissue tumours is more important.Best wishes