I have hard internal lump where drainage tube was inserted to resolve seroma

Dear theswan,
it is hard to tell for sure without an examination. If scar tissue is the cause of your issues, then it can be removed under local anesthesia. If you are considering surgery, I would suggest you consult a board-certified plastic surgeon. Only after a thorough examination, you will get more information and recommendations.
Daniel Barrett, MDCertified, American Board of Plastic SurgeryMember, American Society of Plastic SurgeryMember, American Society of Aesthetic Plastic Surgery

This area of scar tissue may need to be excised and allow a new scar, hopefully thinner and flatter, to heal in its place. Please discuss this with your surgeon.

I'm sorry to hear of the discomfort you are experiencing from the lump of scar tissue. Many times the tissue will need to be removed surgically. However you can consider steroid injections which may help but may not take it away completely. Visit with a board certified plastic surgeon near you for an evaluation.

Most likely the only way to remove the scar tissue is surgically.
I suggest you follow up with your provider or schedule a few in person consultations with other plastic surgeons in your community.
Best,
Mats Hagstrom, MD.

I'm sorry to hear about the discomfort you're experiencing following your tummy tuck and muscle repair in 2016. Developing a seroma is a known complication, and while it's good to hear that issue was resolved, the fibrous lump at the drainage tube site causing you pain is understandably concerning. Here's what you might consider:
Non-Surgical Treatments: Consider steroid injections or physical therapy to soften and reduce scar tissue.Surgical Removal: If the lump is resistant to other treatments, discuss the possibility of surgical removal with a specialist.Pain Management: Use prescribed or over-the-counter medications as recommended by your doctor.Regular Monitoring: Keep track of any changes in the lump and consult your healthcare provider with updates.