A doctor can do fine needle aspiration in the office by inserting a slender needle into the area of concern and drawing out (aspirating) either fluid from a cyst or a small amount of tissue from a solid mass. Cells from a mass, and sometimes fluid from a cyst, is then sent for microscopic evaluation to determine whether cancer is present. Fine needle aspiration is most commonly used to drain a breast cyst that feels tender or sore. If the cyst is a simple cyst (one that looks clear in an ultrasound exam) and isn't tender, it doesn't require aspiration.
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