What does it mean if I feel a small round ball under my armpit, and what should I do?

Generally, feeling a small round lump under the armpit may be caused by accessory breast tissue, folliculitis, lymphadenitis, sebaceous cysts, lipomas, or other conditions. Patients should seek timely medical evaluation at a reputable hospital to determine the cause and receive appropriate treatment. The specific explanations are as follows:

1. Accessory Breast Tissue: Accessory breast tissue refers to breast tissue appearing in areas outside the normal breast region in females. This tissue may proliferate or regress with the menstrual cycle. The armpit is one of the common locations for accessory breast tissue, so the small round lump felt may be accessory breast tissue. Accessory breast tissue typically does not pose serious health risks, but in some cases, surgical removal at a reputable hospital may be necessary to avoid the risk of malignancy.

2. Folliculitis: Folliculitis is an inflammation caused by bacterial infection of hair follicles, which may result in red, swollen, painful lumps under the armpit. These lumps are usually accompanied by blocked follicular openings and increased local inflammation, and may feel painful or tender upon touch. Patients may use medications such as erythromycin ointment, fusidic acid sodium ointment, or mupirocin ointment as directed by a physician.

3. Lymphadenitis: Lymph nodes are important components of the immune system. When the body experiences infection or inflammation, lymph nodes may swell and become painful. The armpit is one of the regions with a high concentration of lymph nodes, so lymphadenitis may cause the sensation of a small round lump in the armpit. Patients may use medications such as tetracycline tablets, roxithromycin capsules, or cefalexin capsules as directed by a physician for treatment.

4. Sebaceous Cyst: A sebaceous cyst is a retention cyst formed due to blockage of the sebaceous gland duct. These cysts are typically located under the skin, vary in size, have a smooth surface, and may feel elastic or firm upon palpation. The armpit is one of the common sites for sebaceous cysts, so the small round lump felt may be a sebaceous cyst. In such cases, patients may undergo cyst excision surgery at a reputable hospital.

5. Lipoma: A lipoma is a common benign soft tissue tumor composed of mature fat cells. These tumors are typically located subcutaneously, vary in size, have a smooth surface, and may feel soft or slightly elastic upon palpation. The armpit is one of the common locations for lipomas, so the small round lump felt may be a lipoma. Lipomas generally do not require special treatment, but if the tumor is large or affects appearance, surgical removal at a reputable hospital may be considered.

In daily life, it is important to maintain good lifestyle habits, regular作息 (作息 should be translated as "作息 habits" or "daily routines"), and ensure sufficient sleep to maintain normal physiological functions. Additionally, it is important to engage in regular physical exercise to enhance personal immunity.