There are several common reasons for a sudden growth of a bag on the foot: a. The patient’s accidental sprain during strenuous exercise can cause serious injury to the soft tissue at the ankle, locally accompanied by hematoma formation. Within 24 hours, ice can be applied, and after 24 hours, local hot compresses can be given, or drugs such as swelling and pain can be taken orally, which can promote the absorption of the hematoma mass more quickly. If the foot mass is formed by sebaceous cyst and infection, the mass will be accompanied by pain and redness, it is recommended to give vital iodine wet gauze or ichthyolite ointment to promote the complete liquefaction of the mass and perform abscess incision and drainage. Third, adolescent patients with bone tumor lesions forming masses in the feet are recommended to undergo surgery to remove the masses as soon as possible, combined with local radiotherapy treatment if necessary.