Melanin deposits on the inner thighs of girls may be a normal physiological phenomenon, but it may also be a symptom caused by diseases such as acanthosis nigricans. Patients can eliminate it through general treatment, medication, physical therapy and surgery. 1. Physiological phenomenon: girls are prone to local skin pigmentation due to the increase in sex hormone level after puberty. The inner thigh melanin deposition caused by physiological factors generally do not need to be deliberately eliminated. Patients can change their habits and control their weight appropriately. Patients with treatment needs can use hydroquinone cream and other topical drugs, and if necessary, can use laser and other physical therapy to promote the elimination of local melanin. 2. Acanthosis nigricans: Acanthosis nigricans is a kind of skin disease with deepening skin color and papillary or velvety thickening of the skin. Acanthosis nigricans occurs in a wide range of areas. As a result, patients with acanthosis nigricans can develop melanin deposits on the inner thighs. Patients with acanthosis nigricans should control their diet, correct obesity, and get enough sleep. For benign patients, topical topical medications such as retinoic acid ointment and salicylic acid ointment can be used. Patients induced by malignant tumors need to be treated for the tumor, such as surgical treatment to remove the tumor. Patients need to note that all the above drugs should be used under the guidance of a doctor. When melanin deposits appear on the inner thighs of girls, they should go to the hospital in time and under the guidance of doctors for regular treatment.