Diagnosis

Diagnosis of a breast cyst usually includes a breast exam; imaging tests, such as a breast ultrasound or mammogram; and possibly fine-needle aspiration or a breast biopsy.

Breast exam

After discussing your symptoms and health history, your doctor will physically examine the breast lump and check for any other breast abnormalities. Because your doctor can't tell from a clinical breast exam alone whether a breast lump is a cyst, you'll need another test. This is usually either an imaging test or fine-needle aspiration.

Imaging tests

Needed tests may include:

• Mammography. Large cysts and clusters of small cysts can usually be seen with mammography. But microcysts can be difficult or impossible to see on a mammogram.
• Breast ultrasound. This test can help your doctor determine whether a breast lump is fluid filled or solid. A fluid-filled area usually indicates a breast cyst. A solid-appearing mass most likely is a noncancerous lump, such as a fibroadenoma, but solid lumps also could be breast cancer.

Your doctor may recommend a biopsy to further evaluate a mass that appears solid. If your doctor can easily feel a breast lump, he or she may skip imaging tests and perform fine-needle aspiration to drain the fluid and collapse the cyst.

Fine-needle aspiration

During a fine-needle aspiration, your doctor inserts a thin needle into the breast lump and attempts to withdraw (aspirate) fluid. Often, fine-needle aspiration is done using ultrasound to guide accurate placement of the needle. If fluid comes out and the breast lump goes away, your doctor can make a breast cyst diagnosis immediately.

• If the fluid is not bloody and has a straw-colored appearance and the breast lump disappears, you need no further testing or treatment.
• If the fluid appears bloody or the breast lump doesn't disappear, your doctor may send a sample of the fluid for lab testing and refer you to a breast surgeon or to a radiologist — a doctor trained to perform imaging exams and procedures — for follow-up.
• If no fluid is withdrawn, your doctor will likely recommend an imaging test, such as a diagnostic mammogram or ultrasound. The lack of fluid or a breast lump that doesn't disappear after aspiration suggests that the breast lump — or at least a portion of it — is solid. A sample of the tissue may be collected to check for cancer.