IntroductionBreast fibroadenoma is a common benign tumor in women, with an incidence rate of approximately 10%[1]. However, cases involving ductal carcinoma in situ (DCIS) within the tumor are relatively rare, with reported incidence rates below 1% in the literature[2]. DCIS refers to malignant proliferation of epithelial cells confined to the ducts, which has the potential to develop into invasive cancer[3]. When DCIS occurs within a fibroadenoma, its benign clinical and imaging features often mask the malignant component, leading to diagnostic challenges before surgery. Currently, most reported cases worldwide are unilateral[4,5]. This article presents a detailed case of DCIS identified within a bilateral breast fibroadenoma confirmed by pathology, exploring its clinical-pathological characteristics, diagnostic approaches, and treatment strategies to enhance clinicians’ understanding and improve management of such rare case.