There is a hard lump in the armpit of men, and there is pain, it may be the following two reasons: 1, may be the armpit of sebaceous cysts, also commonly known as powder tumor, mainly because the sebaceous glands appear blocked, which leads to local infection, inflammation, over time can have a layer of envelope, wrapped inside is some powder inflammatory substances, and lead to a swelling, generally can do local ultrasound, can be clear The diagnosis. If the pain is severe or the inflammation is strong, there may be local redness, swelling, heat, pain, and even purulent infection.2. The lymph nodes in the axilla are enlarged, which may be induced by infectious inflammation in the upper extremities or around the axilla, or may be caused by malignant tumors in the thorax, which cause pain in the lymph nodes through lymphatic metastasis.