Soybean-sized hard lumps under the neck skin are usually symptoms of sebaceous cysts, lipomas, and enlarged lymph nodes. 1. Sebaceous cyst: It is a benign skin tumor, which is formed by the follicle of sebaceous gland duct blockage, sebum can not be metabolized out of the body normally, and the accumulation of cysts. It is mainly manifested as hard lumps under the skin. 2. Lipoma: it is a kind of common benign soft tissue tumor, which may be related to abnormal fat metabolism, and it occurs in limbs and trunk, manifesting as soft lumps under the skin, which may be single or multiple. 3. Enlarged lymph nodes: usually caused by inflammation or tumor in neighboring organs or tissues, local inflammation will lead to enlarged lymph nodes, which may be accompanied by pressure and pain, usually smooth to the touch and not adherent to the surrounding tissues. Specifically need to go to the hospital, clear diagnosis and follow the doctor’s instructions for treatment.