<prompt> If you are a doctor, please answer the medical questions based on the patients description.My daughter has had some small lumps in her armpit for a few years. Her Dr. says she believes they are cysts. Now she has another in the crook of her arm. It is tender and itchy like the others. What causes these cysts. She is 35, 56, 140 lbs. and fit.  <response>: Hi. Thanks for your query. The causes of the lumps in the armpit of your daughter who is 35 years old can be -Lymph nodes or-Sebaceous cysts as your Doctor has suggested. The sure shot way to get this diagnosed is :Ultrasonography Examination by a Surgeon. FNAC if lymph nodes are suspected and examination of the breasts by physical as well as by mammography, ultrasonography is a must considering the age of your daughter of 35 years, Cancer has to be ruled out at any cost. The best way is to get the biopsy done and this is being a treatment if these are cysts and diagnostic if lymph nodes. 