Microcalcification

Microcalcifications are calcium deposits smaller than 0.5 millimeters — roughly the size of a grain of salt. They form as a natural byproduct of cell activity in the breast and are extremely common. The vast majority of microcalcifications are benign, the result of aging, prior inflammation, or normal cellular processes. However, some patterns of microcalcifications are associated with abnormal cell growth, including ductal carcinoma in situ (DCIS) or early invasive breast cancer.

Radiologists evaluate microcalcifications based on their distribution (scattered throughout the breast vs. clustered in one area), their morphology (rounded and smooth vs. irregular or branching), and their density. Clustered, irregularly shaped microcalcifications arranged in a linear or branching pattern tend to attract more concern because they can indicate calcium deposited in or around abnormal ducts. Scattered, round, or popcorn-shaped calcifications in both breasts are almost always benign.

When the pattern of microcalcifications is uncertain or suspicious, a biopsy — usually a stereotactic core needle biopsy guided by mammography — is performed to sample the calcifications and examine them under a microscope. This is the only way to know with certainty whether a cluster of microcalcifications represents a normal process, a benign condition, or early cancer.

Microcalcifications are among the most common reasons women are called back for additional imaging after a screening mammogram. Getting a callback can be anxiety-provoking, but it is important to know that the vast majority of microcalcification callbacks turn out to be benign. Your radiologist is doing their job by investigating patterns that deserve a closer look.

When a biopsy is recommended for microcalcifications, it can feel alarming — but this is often how very early cancers like DCIS are caught before they have a chance to become invasive. Detecting and treating DCIS at this stage, while it is still confined to the ducts, is one of the clearest examples of how mammography saves lives. Understanding what microcalcifications are — and what they are not — can make the follow-up process feel less frightening.