“Fibroglandular” is a term often encountered in breast health, especially when reviewing mammogram results. It refers to a specific type of breast tissue. Understanding this term is important because it relates to how breast tissue appears on imaging and can influence breast cancer screening.
Understanding Fibroglandular Tissue
Fibroglandular tissue in the breast is a combination of two primary components: fibrous connective tissue and glandular tissue. The “fibro” part denotes fibrous connective tissue, which provides support and structure to the breast, similar to ligaments. The “glandular” part refers to the milk-producing glands, known as lobules, and the ducts that transport milk to the nipple. These tissues collectively form the functional units of the breast.
This tissue type is distributed throughout the breasts, and its proportion varies among individuals. Fibroglandular tissue plays a fundamental role in breast function, particularly in lactation.
Fibroglandular Tissue and Breast Density
The amount of fibroglandular tissue relative to fatty tissue determines breast density, a characteristic noted on mammograms. Fatty tissue appears dark or transparent on a mammogram, making it easier to visualize any abnormalities. In contrast, fibroglandular tissue appears white on mammographic images.
Breast density is categorized using the Breast Imaging Reporting and Data System (BI-RADS), which classifies breasts into four levels:
Category A: Almost entirely fatty breasts (about 10% of women).
Category B: Scattered areas of fibroglandular density (approximately 40% of women), with some dense areas mixed with mostly fatty tissue.
Category C: Heterogeneously dense breasts (around 40% of women), where most of the breast tissue is dense.
Category D: Extremely dense breasts (about 10% of women).
Implications for Breast Health Screening
Dense breast tissue, due to a higher proportion of fibroglandular tissue, can complicate mammogram interpretation. Both dense tissue and potential cancerous tumors appear white on a mammogram. This overlap can create a “masking effect,” making it challenging for radiologists to distinguish between healthy dense tissue and a hidden tumor.
Beyond the masking effect, having dense breasts is also associated with a slightly increased risk of developing breast cancer. While the exact reasons are still being researched, it is believed that the higher amount of glandular tissue may contribute to this elevated risk. For individuals with dense breasts, additional screening methods may be recommended to supplement mammography, such as breast ultrasound or MRI. It is important for individuals to discuss their breast density and appropriate screening strategies with their healthcare provider.