If there are visible hard bumps under the armpits, the clinical underarm area, when touched, the possibility of multiple etiologies is considered. If a patient develops hard bumps in the armpit before menstruation, they may be caused by increased estrogen levels that stimulate the mammary glands, which in turn produce hyperplastic lesions, usually recovering on their own after menstruation, without the need for special treatment. In addition, we do not rule out the possibility that some of the disease factors may cause hard bumps under the armpit, and should be carried out to treat the cause. Common causes and treatments 1, axillary folliculitis: If the patient’s armpit has obvious hard bumps when touched and is accompanied by red papules centered on hair follicles, it can be judged as axillary folliculitis. This is mainly due to heavy underarm sweating and lack of proper hygiene and cleanliness. Patients need to go to the hospital promptly and follow the doctor’s prescription for topical mupirocin ointment for anti-inflammatory and analgesic treatment, as well as internal antibiotic medication such as cefdinir and azithromycin. In some patients with boils or carbuncles, surgical incision of the lesion is required to drain the pus. 2. Axillary lymph node enlargement: (1) Due to general bacterial infection causing axillary lymph node enlargement, manifesting as redness, swelling, heat, pain and other manifestations, axillary lumps, i.e. hard bumps, some serious cases may be complicated by cellulitis, bacteraemia, acute glomerulonephritis and other conditions, so patients need to take active treatment in a timely manner. Therefore, patients need to take prompt and active treatment, using antibiotics such as amoxicillin and cefixime capsules to relieve acute inflammation as prescribed by the doctor. If the condition progresses to lymph node abscess, puncture and drainage is required. In addition, some patients may heal themselves without treatment; (2) axillary lymph node enlargement due to specific bacterial infection, such as axillary lymph node tuberculosis, which is characterized by local lymph node enlargement, hardening, or even fusion into a mass, and systemic manifestations such as poor circulation and night sweats. (3) breast cancer axillary lymph node metastasis, axillary lymph node enlargement, hard texture, can be fused into a mass, need to be confirmed by puncture biopsy or lymph node biopsy; (4) systemic lymphatic system tumor caused by axillary lymph node enlargement, such as lymphoma, also manifested as axillary lymph node enlargement, hard texture, in addition to systemic hematologic abnormalities In addition to systemic blood system abnormalities, sometimes it is necessary to cut the enlarged lymph nodes and send them for pathological examination to confirm the diagnosis. 3. subcutaneous lipoma: a common benign tumor of subcutaneous tissue, mainly caused by abnormal proliferation of fat cells, patients have hard bumps when touched in the neck, shoulders, back and armpits, and the treatment plan varies from person to person. If the patient has hard bumps in the armpit with no discomfort, no treatment is needed and observation is sufficient. If there is obvious pressure pain, or if it grows too fast in a short period of time, it is necessary to perform lipoma excision and send it for pathological examination after surgery to determine its benign and malignant nature; 4. sebaceous cyst: also known as powder tumor, it is a sebaceous cyst caused by the occlusion or narrowing of the mouth of the cystic duct of the sebaceous gland, forming a retention cyst, which also manifests itself as a hard underarm pimple, but this swelling is usually located under the skin, with adhesions to the skin and a black head in the center, and when squeezed, there can be white bean curd The swelling is usually located under the skin, with a black head in the center, and when squeezed, there can be white bean curd-like material extrusion. It is a benign skin disease that requires surgery to remove. When a patient finds a hard bump in the flesh under the armpit, he or she should not take it lightly and should seek medical attention in a timely manner to clarify the specific cause so that the condition does not develop and delay treatment.