If you have a small armpit and neck, it may be caused by the following two reasons: 1. It may be a local sebaceous cyst, i.e., a powdery tumor, generally because the local sebaceous gland of the skin is blocked after the formation of chronic inflammation, thus forming a layer of envelope wrapped inside the powdery inflammatory material and the formation of a subcutaneous swelling, generally if there is no inflammation, pressure does not appear pain. If there is an infectious inflammation, there will be redness, pain or even pus. 2, may be local lymph nodes, if it is a relatively thin crowd and subcutaneous fat is thin, may feel their own lymph nodes in this area, if there is no swelling, hardening and pressure pain, generally do not need special treatment. If the lymph nodes become hard and painful, it may be caused by inflammation, so we must do local ultrasound to make a clear diagnosis and then do the corresponding treatment.