American Board of Internal Medicine (ABIM) Certification Practice Exam

For individuals under 30 years old presenting with a breast lump, what is the preferred imaging modality?

1. Mammography

2. CT scan

3. Ultrasound

4. MRI

The correct answer is: Ultrasound

For individuals under 30 years old who present with a breast lump, ultrasound is the preferred imaging modality. This choice is primarily due to the dense breast tissue commonly found in younger women, which can obscure the details on a mammogram and limit its effectiveness. Ultrasound is particularly valuable in this age group because it helps differentiate between solid masses, such as cysts or potential tumors, and benign lesions with a high sensitivity for detecting cystic changes. Mammography, while effective for breast cancer screening in older women, is less useful in younger populations due to the higher proportion of glandular tissue compared to fatty tissue in their breasts. A CT scan is not typically utilized for breast imaging as it is not specific to breast pathology and exposes patients to unnecessary radiation. MRI is a highly sensitive tool and can be beneficial in certain contexts, such as for high-risk patients or in evaluating known lesions, but it is not the first-line imaging for a palpable breast lump in those under 30. In summary, the selection of ultrasound for evaluation of breast lumps in younger patients is grounded in the need for clarity in imaging, the characteristics of breast tissue, and the goal of minimizing radiation exposure while providing accurate information about the nature of the breast abnormality.