Carcinoma left breast
On both occasions round 1 and round 2 screening, the MLO views were unremarkable. On the round 2 screening, the patient was recalled for additional imaging. The ultrasound study was read as normal and the patient was returned to screening.
The patient presents two years after round 2 screening for diagnostic mammography with a palpable mass in the left breast as well as nipple retraction. The patient has multicentric carcinoma of the left breast with positive axillary lymph nodes on FNA.
Teaching point: as a general rule, no postmenopausal breast should be doing anything except involuting i.e. gland gets replaced by fat unless the patient is on exogenous hormone therapy. Carcinomas do not have to show a mass or calcifications on mammography: a developing density is a well-known presentation. The density may be very subtle and if you don't look at the oldest previous study you will miss them... as you will if you simply look at last year's study. The fact that the ultrasound is called "negative" means you need an additional study (MRI) or FNA/biopsy to confirm there is no malignancy. You cannot simply say normal ultrasound and return to screening.
Any postmenopausal breast that shows increased density or focal asymmetry deserves careful thought and work up.