Small bumps in the armpits are considered to be caused by epidermal cysts, lymphadenitis, and soft fibromas. 1. Epidermoid cyst: Epidermoid cyst is a kind of skin cyst, which may be related to skin injury, embryonic ectopic and other factors. The patient’s skin will appear dome-shaped elevated skin swelling, commonly in the face, trunk and other places. 2. Lymphadenitis: Lymphadenitis is the inflammation of lymph nodes caused by infection, hemolytic streptococcus and staphylococcus aureus are the most common causative organisms. Patients will have localized pain and lymphatic enlargement, and in severe cases, lymph node abscess will appear, which is common in armpit, neck and other places. 3. Soft fibroma: the cause of soft fibroma is still unclear. Patients mainly manifest that there is a skin growth with a tip that is higher than the skin surface, which is commonly found in armpit and neck. There are many reasons for small bumps in armpits, and it is suggested that patients should consult doctors for examination to clarify the causes of the disease.