What causes light brown patches on the lower leg, and what should be done about it?

Generally, the appearance of light brown patches on the lower leg may be caused by factors such as sun-induced pigmentation, friction irritation, stasis dermatitis, post-eczematous pigmentation, or lichen planus. Depending on the specific situation, patients can choose appropriate measures such as general care or medication to improve the condition. A detailed analysis is as follows:

1. Sun-induced pigmentation

When the lower legs are exposed to sunlight for prolonged periods, ultraviolet rays stimulate melanocytes to become active, leading to melanin deposition and the formation of light brown patches. It is recommended to wear long pants or apply sunscreen when going outdoors to avoid direct sun exposure, and to consume more fruits and vegetables rich in vitamin C in daily diet.

2. Friction irritation

Wearing tight pants over a long period or repeated friction against the skin of the lower leg can cause localized thickening of the stratum corneum accompanied by pigmentation, resulting in light brown patches. Switching to loose, soft clothing to reduce friction and applying moisturizing lotion after bathing can help nourish the skin.

3. Stasis dermatitis

Impaired venous return in the lower limbs leads to blood stagnation, causing skin hypoxia and subsequent inflammation that results in light brown patches, often accompanied by itching. Under medical guidance, patients may take medications such as micronized purified flavonoid extract (e.g., Daflon) or diosmin tablets, apply topical polysulfated glycosaminoglycan cream, and elevate the legs during rest.

4. Post-eczematous pigmentation

After healing of eczema on the lower leg, inflammatory stimulation causes melanocytes to produce excess melanin, leaving behind light brown patches. As directed by a physician, topical treatments such as hydroquinone cream or tretinoin cream may be used, along with oral vitamin E soft capsules. Avoid scratching previously affected eczema areas.

5. Lichen planus

Abnormal immune responses trigger skin inflammation; after lesion resolution, light brown hyperpigmented patches may remain, often with mild itching. Under medical supervision, topical tacrolimus ointment or mometasone furoate cream may be applied, and oral acitretin capsules taken. Spicy and irritating foods should be avoided.

In daily life, proper sun protection for the lower legs should be maintained, and comfortable clothing chosen to minimize irritation. Ensure good circulation in the lower limbs by avoiding prolonged standing or sitting. Monitor changes in the patches, and seek timely medical evaluation and treatment if they enlarge or itching worsens.