Indented discolored spot on my upper arm

I recently noticed a discolored indented spot on my upper arm.. It is about 1 1/2 inch long and 1/2 inch wide. Very irregular shape similar to a birthmark. The color of it is a little bit darker than my skin color. I know this sounds weird, but if I press down on it, it feels like part of my musle underneath is gone. Just where the discolored spot is though. Its clearly indented; if I rub my fingers over it, there is definitely a dip in  my skin. I have never had anything like this and I'm only 24 years old, any experience or advice would be great. Thank you!

[Bhupinder Kaur, MD]

Hello,
Did you suffer any injury on the area as then it can be due to atrophic scar or depressed scar. Other than it can be due to any connective tissue disorder causing loss of muscle mass in your case. I suggest you to get it examined from a dermatologist to confirm the diagnosis.

It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.