Collagenous spherulosis is an uncommon, usually incidental finding in breast tissue removed for a variety of reasons. A case of collegenous spherulosis, presenting as mammographic microcalcifications and diagnosed by stereotactic core needle biopsy, is used to address this relatively new diagnosis modality for the evaluation of non-palpable breast lesions. In this case, the microcalcifications were present exclusively within aollagenous spherulosis and no other abnormalities were obseved. With the increasing use of stereotactic core-needle biopsy it is important that pathologies become familier with this technique and its limitations, as well as the unusual lesions it may uncover.