microcalcification

noun

mi·​cro·​cal·​ci·​fi·​ca·​tion -ˌkal-sə-fə-ˈkā-shən 

: a tiny abnormal deposit of calcium salts typically in the breast that is often benign but may be an indicator of breast cancer especially when appearing in compact clusters or a linear or branching pattern

A mammogram detects microcalcifications, which are tiny specks of calcium in the breast that may indicate cancer even before actual tumors form.

—Andrew Weil, Self Healing