A small bulge on the inside of the back of the hand that hurts when pressed could be a symptom caused by skin boils, epidermal cysts, tendon sheath cysts, and other diseases. Patients should undergo general treatment, medication, surgery, etc. under the guidance of a doctor. 1. Skin boils: Boils are acute suppurative inflammatory skin diseases of individual hair follicles and their affiliated sebaceous glands, which may appear locally with symptoms of redness, swelling, heat and pain. Patients can use mupirocin ointment, fusidic acid cream and other topical antibiotics. In severe cases, local incision and drainage can be carried out when abscesses are formed. 2. Epidermoid cysts: Epidermoid cysts are a kind of dermal cysts containing keratin, which can occur in any part of the human body. The lesions are mostly isolated intradermal or subcutaneous nodules, which can be painful when combined with bacterial infection. Patients with epidermal cysts can undergo surgical excision, along with the use of penicillin, ampicillin and other antibiotics to prevent postoperative infection. 3. Tendon sheath cysts: Tendon sheath cysts are cystic lesions that occur in the tendon sheath, mainly manifested as small lumps on the tendon sheath, and may produce swelling and pain when pressed. Patients can be treated with general therapy such as needle compression and puncture injection, and patients with localized pain can take oral aspirin and other non-steroidal anti-inflammatory drugs. Surgical excision can be performed if conservative treatment is ineffective. Patients need to pay attention to the above drugs should be used under the guidance of a doctor. Patients with a small bulge inside the back of the hand that hurts when pressed should go to the hospital in a timely manner, under the guidance of the doctor for regular treatment. All of the above drugs should be used in accordance with the doctor’s instructions.