The black marks on the knees are considered to be caused by the accumulation of stratum corneum and post-inflammatory hyperpigmentation.
1. Corn layer accumulation: knee long black marks are mainly caused by the long-term accumulation of local skin aging of the stratum corneum, which will lead to the phenomenon of melanin precipitation at the knee.
2. Post-inflammatory hyperpigmentation: post-inflammatory hyperpigmentation is a kind of acquired pigmentation abnormality disease, usually caused by acute or chronic inflammation of the skin. If the knee area has suffered from trauma or dermatitis and other diseases, may stimulate the melanocytes in the skin, so that its function is hyperactive, synthesize more melanin, resulting in local black marks.
Black marks on the knee are usually caused by hyperpigmentation after keratinization or inflammation, and if you feel that it affects your appearance, it is recommended to seek medical attention.