A pimple on the patient’s eyelid may be caused by mosquito bites, blepharitis, chalazion, eyelid tumors and so on. 1. Mosquito bites: When mosquitoes bite into the eyelid area, the patient’s eyelids may appear swollen, usually accompanied by itching and redness and other symptoms. 2. Blepharitis: Blepharitis, also known as erysipelas, is an acute suppurative inflammation of the eyelid glands. The patient’s eyelids may be red, swollen, hot, hard and painful, and there may be swelling of the eyelids. 3. Blepharophalangeal cyst: Blepharophalangeal cyst refers to idiopathic aseptic chronic granulomatous inflammation of the blepharophalangeal glands, and the patient mostly presents with a round lump under the eyelid skin, which is usually painless. 4. Eyelid tumor: patients with dermoid cysts, hemangiomas and other tumors of the eyelids can also lead to the appearance of bulging eyelid swelling. It is recommended that patients with eyelid lumps and other discomforts should consult the doctor in time to evaluate their conditions and follow the doctor’s instructions.