Mysterious rash on the back of my neck just above the shirt?

One week ago, a rash appeared below my hair line and just above my t-shirt line. It is kind of blotchy and ends before reaching the sides of my neck. It is made up of darker than skin color spots scattered around the back of my neck and it doesn't itch. I just discovered it when I noticed it in front of the mirror. I just started using a prescribed Triamcinolone Acetonide Cream usp, 0.1% because of another rash that is on the inside of my arms that none of the doctores know what it is. So if anybody could help me with that to that would be great. Thanks.

[Bhupinder Kaur, MD]

Hello,
I cannot confirm anything without examination but it can be drug eruption or due to hyperpigmentation skin, one possibility being acanthosis nigricans.

This darkening can also occur when an excess of melanin, the brown pigment that produces normal skin color, forms deposits in the skin.
Acanthosis nigricans presents as symmetrical, hyperpigmented, velvety plaques mostly in the folds of skin. It is not itchy and is characterized by hyperpigmentation. My sincere advice is to consult a dermatologist. The other possibility is of Addison’s disease.

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.