There is a hard lump inside the armpit of a woman, press the pain to consider folliculitis, lymphadenitis, tumor metastasis, etc., the patient should consult a doctor in a timely manner to clarify the cause of the disease, and then carry out the appropriate treatment. 1. Folliculitis: caused by viruses, bacteria and other infections to the hair follicles are mainly involved in inflammatory skin diseases, occurring in the armpit can be manifested as a localized pain in the hard lumps, itching, such people can be localized use of ketoconazole, cefadroxil and other drugs for treatment. 2. Lymphadenitis: pathogenic bacteria from the skin, mucous membranes and other places to invade the lymph nodes caused by lymph node enlargement, the patient will have localized hard lumps when pressed pain, some patients also have fever and other symptoms, can use penicillin, erythromycin and other drugs for treatment. 3. Tumor metastasis: a hard lump inside the armpit of a woman may be caused by lymph node metastasis of malignant tumors, and such patients will also have symptoms of the primary site of the tumor, and should be actively prepared for surgical treatment. All the above medicines and treatments should be carried out under the guidance of doctors.