What is the most common breast tumor in women under age 30?

• A. Fibroadenoma
• B. Cystic mastopathy
• C. Sclerosing adenosis
• D. Lipoma

Answer: (A)

Young women most commonly develop a benign breast tumor called a fibroadenoma. This lesion arises from fibroepithelial tissue and is typically hormone-responsive, often presenting as a small, firm, painless, and very mobile lump. Because it is well defined and solid, ultrasound usually shows a solid, homogeneous, well-circumscribed mass that is hypoechoic with a possible thin capsule and gentle lobulations; posterior acoustic enhancement is common. These features, along with its prevalence in the under-30 age group, make fibroadenoma the most likely breast tumor in this population.

Cystic mastopathy refers to fibrocystic changes with cyst formation, which can cause pain and multiple cysts rather than a discrete tumor. Sclerosing adenosis is a proliferative fibrocystic change that can mimic malignancy on imaging but is less common as a distinct, palpable tumor in young women. Lipoma is a fatty tumor and is typically softer, more compressible, and has fat-density characteristics on imaging, making it less likely than a fibroadenoma in this age group.