Glossary — F

A false positive is a screening or diagnostic test result that indicates the presence of a condition — such as cancer — when the person does not actually have that condition. False positives lead to additional testing or procedures to rule out disease, which can cause anxiety but are a recognized and manageable part of screening programs.

A fibroadenoma is a noncancerous (benign) breast lump composed of a mixture of glandular and fibrous connective tissue. It is the most common benign breast tumor, particularly in women in their 20s and 30s, and typically feels like a smooth, firm, rubbery lump that moves easily under the skin.

Fibrocystic breasts is a benign condition in which breast tissue contains an excess of fibrous connective tissue and fluid-filled cysts, giving the breasts a lumpy, uneven texture. It is extremely common — affecting more than half of women at some point in their lives — and is associated with hormonal fluctuations rather than disease.

Fibroids — medically known as uterine leiomyomas — are noncancerous tumors made of smooth muscle and connective tissue that grow in or around the uterus. They are extremely common, affecting up to 80 percent of women by age 50, and can range from pea-sized to large enough to distort the uterus. Many women with fibroids have no symptoms; others experience heavy periods, pelvic pressure, or fertility challenges.

Fine needle aspiration (FNA) is a type of biopsy in which a thin, hollow needle is inserted into a lump or mass to withdraw a small sample of cells or fluid. The sample is then examined under a microscope by a pathologist to determine whether the tissue is benign, cancerous, or indeterminate. FNA is fast, requires no incision, and is usually performed in an outpatient setting.

Fluoroscopy is an imaging technique that uses a continuous X-ray beam to produce real-time, moving images of internal structures. Unlike a standard X-ray, which captures a single still image, fluoroscopy acts like an X-ray "movie," allowing physicians to watch organs and instruments move in real time — particularly useful during procedures involving catheters, contrast agents, or swallowing studies.