Dark dry patch of skin on lower back

I have a patch of darkened dry skin on my lower back. It is about the size of a CD. I am 18 years old and male. I have not exposed my back to the sun and the patch has been there for about a couple of months. The patch is only somewhat darker than the rest of my body (as if it were slightly tanned). It gets flaky when my skin is dry. It does not bother me in any way, no itching, no rash, etc. It's just rough and dry. Any idea what this is?

[Bhupinder Kaur, MD]

Hello,
One possibility that is coming to my mind is of nostalgia parasthetica. It also presents as itchy, dark pigmented patch seen one the back or trunk. Sensation to light touch, temperature, vibration, and two-point discrimination may be normal or abnormal.

Biopsy skin can help in confirming the diagnosis. Also if there are any other systemic symptoms, then systemic diseases like scleroderma and SLE have to be ruled out. For that you need to consult your dermatologist.

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.