Darkening of the skin in the follicular area of the legs may be associated with diseases such as perifollicular keratosis and small spiny congestion. 1. Perifollicular keratosis: It is a chronic follicular keratinizing skin disease, which will be clinically manifested as small skin-colored or reddish papules in the follicle area, which may be topped with light brown keratin plugs. Keratosis pilaris is related to heredity, and it has no effect on the body except that it affects aesthetics, and can be treated with topical medications such as retinoic acid cream when necessary. 2. small spiny hair congestion disease: also known as cui hair black head acne, adult male hair, lesions can occur in any part of the body, the main manifestation of clusters of cui hair wrapped in keratinized hair follicles, the formation of a black spiny papules, the cause of this disease is not known, and may be associated with congenital abnormalities of the development of hair papillae. Due to the existence of individual differences, the specific circumstances need to ask the doctor for a face-to-face consultation.