Low-grade ductal carcinoma in situ (DCIS) arising in a fibroadenoma of the breast during 5 years follow-up: A case report.

RATIONALE Fibroadenoma (FA) is a common type of benign breast tumors but ductal carcinoma in situ (DCIS) rarely arises within this tumor type. PATIENT CONCERNS This case report presents a non-symptomatic 61-year-old woman with FA that was coincidentally found during a breast cancer screening program performed 5 years ago by her city of residence. She had subsequently been followed-up with mammography and breast ultrasound (US). US showed a slightly enlarged tumor and dynamic magnetic resonance imaging (MRI) indicated malignancy within the FA. DIAGNOSIS The pathological examination revealed low-grade DCIS within the FA. INTERVENTIONS The patient underwent a core needle biopsy followed by breast-conserving therapy with sentinel lymph node biopsy and then postoperative radiation therapy. OUTCOMES Currently, she has been followed-up for 2 years without no signs of recurrence. LESSONS Careful observation with US followed by dynamic MRI is essential in the early diagnosis of DCIS originating in a FA.