Hello. Thanks for writing to us at healthcaremagic Likely we are dealing with a sebaceous cyst here. Cysts such as these are usually asymptomatic and can persist for years, increasing in size ever so slowly. The problem with a sebaceous cyst is that while it is not a problem in itself, it can become infected with bacteria, on and off. A cyst in the underarm area is specially prone to recurrent infections because there is a lot of bacterial flora present in underarm area. Infection would cause the cyst to increase in size, become painful and tender. Fever may arise. Infected cysts would require a course of an oral antibiotics to settle down the infection. Once the infection resolves, it is usually advisable to remove the cyst surgically in order to prevent future infections. Surgery is the only way to get rid of the cyst and is usually a minor procedure under local anesthesia. Therefore you need not feel uncomfortable about surgery and it is in your own interest to get rid of it. Regards