The skin discoloration found over knuckles can stem from multiple possible medical conditions including:
Pigment changes due to sun exposure or friction
The condition of hyperpigmentation develops because of Vitamin B12 deficiency and other vitamin deficiencies.
Addison’s disease produces dark skin patches throughout the body with the knuckles and elbows showing the most prominent changes
Eczema or other skin conditions
Consult a doctor if your knuckles turn dark for no apparent reason or if dark skin patches expand across your body.
Sources
Health.com, 2025
Medical News Today, 2024
Disclaimer: This article is for informational purposes only and is not a substitute for medical advice.
