Hello, and thankyou for approaching DoctorSpring with your query.
I have gone through you case and understand your concern.
Please can you answer a few questions so that I can give you an informed opinion.
1) Can you tell me the exact location of the lump, is it along or just above the anal cleft in the midline?
2) Has there been any discharge coming out from the lump?
3) Is it red and does it pain on touching?
4) Does the pain worsen while stretching like bending forward?
5) Are there any pits on the lump or hair protruding from it?
6) Are you overweight an have to sit for long periods of time?
Please reply as a follow up and I shall guide you accordingly.
Thankyou
Patient replied :
Thank you for your reply, it does feel bony I.e. Very hard but you still feel most likely benign. Always had the impression a cyst or lipoma had some give to them?
It parallel along with the midline, no discharge or pus, no abscess. I do sit for most of the day and not overweight, no hairs or pits which I would assumes rules out a cyst,it does hurt a very little when bending over or pressure is applied. Normal skin color. Thx for your prompt reply
Hello,
Yes lipomas are more or less mobile and firm rather than hard. Cysts can get calcified and present hard. There are few reason I would still suspect benign non bony lesion. First of all the pelvic - sacral bone is superficial and flat and there by bony swelling are felt 'very bony'. Not mobile, bone hard.
Second this is the site of repeated impact (by sitting and lying down) so even a lipoma can appear hard. And finally from experience in most cases biopsies of similar lesions reveal soft tissue , not bone. Being said that a physical examination + Xray will be required to be sure. (it could be bit challenging to visualise the swelling in the x ray because of the bony overlap, still).
Hope this helps
Feel free to ask followups/clarifications
Thank you
Patient replied :
Thank you again for your response. One last question and I will close the case. About 2 months after I noticed the lump it got somewhat shorter and flatter or perhaps just shifted position. Is this very typical? Thank you for your time.
Well, it is not typical. But this change in position and size says it is more likely to be a non osseous swelling. (non bony)
Hope this helps. Feel free to ask followups.Thank you