Long bumps under the armpit commonly include sebaceous cysts, lipomas, enlarged lymph nodes, folliculitis, and paronychia. First, sebaceous cysts are located in the subcutaneous shallow, clear boundaries with the surrounding tissues, the local skin surface can be found small black concave line, advocating surgical excision. Second, lipoma. Located in the subcutaneous fat layer, clear boundaries, soft texture, no pain, usually not infected, to surgical excision. Third, enlarged lymph nodes, this kind is mostly caused by trauma to the surrounding tissues. If it is not painful, but hard, it needs to be noted that it is tumor. Fourth, paratesticular glands. Some women may have paratesticular glands, which are characterized by poorly defined borders and soft swellings, which are common bilaterally, and some patients may have swelling and pain during menstruation. Fifth, folliculitis. At first, it is a red papule, which gradually evolves into papule-like pustules, isolated and scattered, with mild self-consciousness and pain. Adults are mainly found in hairy areas, and children are more likely to be found on the head. The above content is for reference only, specific medication, treatment, please refer to the doctor’s guidance.