Snapshot A 58-year-old woman presented to her primary care physician after a screening mammogram revealed calcifications in the left breast. Physical exam revealed no palpable breast lumps or axillary lymphadenopathy. Introduction Overview a neoplastic lesion confined to the breast duct a true premalignancy 50% develop into invasive ductal carcinoma if untreated risk is for both the ipsilateral and contralateral breast Epidemiology Incidence 32.5 in 100,000 women represents ~20% of breast cancer diagnoses in the U.S. Risk factors increasing age nulliparity family history of breast cancer age ≥ 30 or older at birth of first child obesity ETIOLOGY Genetics inheritance increased risk with BRCA1 and BRCA2 mutations mutations 75% of DCIS is estrogen (ER)/progesterone (PR) receptor-positive Associated conditions Paget disease of the breast overlying breast skin changes that may occur in association with DCIS skin crusting and itching Presentation Symptoms asymptomatic Presentation typically no palpable mass on exam +/- nipple discharge +/- overlying breast skin crusting Imaging Mammography indications screening DCIS often detected on screening mammogram findings calcifications in 90% of DCIS linear calcifications associated with more aggressive DCIS granular calcifications associated with less aggresive DCIS breast mass uncommon but occassionally found on mammography (~8% of cases) Ultrasound indications to guide biopsy if lesion is visible on US findings microlobulated mild hypoechoic mass with ductal extension Core or excisional biopsy indications diagnosis following detection of calcifications on mammogram using stereotactic guidance findings proliferation of neoplastic cells within the mammary ductal system 11% will have findings of microinvasion Differential Lobular carcinoma in situ (LCIS) key distinguishing factor e-cadherin expression on histology positive in DCIS and negative in LCIS Invasive carcinoma key distinguishing factor evidence of invasion on biopsy Treatment Medical radiation indications postoperative following lumpectomy endocrine therapy indications ER/PR-positive DCIS to reduce chance of developing invasive cancer especially in patients who did not undergo bilateral mastectomy modalities tamoxifen close follow-up and screening mammography indications all DCIS patients to detect future development of invasive carcinoma Surgical lumpectomy indications relatively smaller masses compared to size of breast ability to get negative margins multicentric disease involving more than one quadrant is a relative contraindication followed by radiation can skip radiation if low-grade DCIS that is < 1-2 cm mastectomy (typically bilateral) indications invasive components on biopsy multicentric disease relatively large masses compared to size of breast patients who prefer bilateral mastectomy in order to reduce risk of future invasive carcinoma Complications Development of invasive carcinoma ~6% risk of recurrence of invasive carcinoma after DCIS treatment in both contralateral and ipsilateral breast Death Prognosis Excellent ~1.7-3% mortality in treated patients