Thanks for the suggestions but i heard hydroquinnone is harmful to the skin.
B12 deficiency is a known cause for knuckle pigmentation.Rarer causes would include 'Addison's' which could present like this.
Do consult your doc.
Hello,
For the dark knuckles, treatment includes various skin creams like hydroquinone, azelaic acid, corticosteroids, tretinoin cream and laser treatment. However these should be used under a medical guidance. Also at night, repair your hands with creams formulated from glycolic acid—a must for improving skin texture and tone. For a more intensive nighttime treatment, apply cream and then cover hands with gloves or socks.
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 dermatologist. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.