Large indent on left buttock bikini line area

Without a photo or the necessary physical exam, my first guess would be autologous fat transfer to fill the dent naturally and evenly.  If the dent is tethered in any way then scar tissue release (a.k.a. subcision) may be required as well.  The procedure may even be done under local anesthesia +/- twilight sedation to avoid the extra recovery of general anesthesia.  Glad to help.  

I have been very pleased with Sculptra as a way to fill out buttock indentations. I find that the procedure requires little to no downtime and is office based. I have done minor dimples to full buttock augmentations, albeit the latter is for people who want a modest augmentation and with little fat to donate. At times, if the indentation is associated with a scar, then subcision or a scar release may also be warranted.

   I have had very good success with fat grafting and scar release techniques in dents due to trauma, development, or after a previous liposuction.Kenneth Hughes, MDLos Angeles, CA

Hello dear!!
Thanks for the question and provided information as well.
Unfortunately, without pictures, it is very difficult to give you a proper answer. l recommend you to make an appointment with a board certified plastic surgeon to talk about your goals and anything you need to know.
Good luck :)

Though the likelihood is low that this would be anything very concerning, I would recommend first making sure you see a doctor who can examine this lesion and make any recommendation regarding the need for a biopsy/removal or imaging. If it is in fact just an irregularity/indent in your tissue, procedures such as scar revision or a small amount of fat grafting are definitely great options to address this. 

Thank you for submitting your question regarding procedures to correct the indent on your left buttocks.  Without proper examination it difficult to say what the best procedure would be.  I recommend scheduling a consultation with a board certified plastic surgeon who performs fat grafting and scar revision.  The indent may have been caused by a trauma to the area.  If this were the case, fat harvested from other sites can be transferred to the depressed area.  The procedure is called fat grafting and could potentially reduce or eliminate the indent.