Fibroadenoma with an unexpected lobular carcinoma in situ: A case report and review of the literature.

Fibroadenoma (FA) is the most common type of breast lesion in young female individuals. Although malignant transformation in FA is rare, there is evidence of an association with breast carcinoma, particularly in middle-aged females with associated risk factors, such as a strong family history and/or BRCA-1/2 mutations. The current study presents the case of a 44-year-old female exhibiting lobular carcinoma in situ (LCIS) arising within an FA. Over the previous 20 years, numerous lumps were detected in the patient's breasts, all of which were clinically diagnosed as FA and expectantly managed. One year prior to presentation, the patient's father was diagnosed with esophageal cancer, older sister with kidney cancer and the patient herself with a benign ovarian teratoma. The patient presented with one lump in each breast and monitoring was performed using ultrasonography (US). US detected an increase in the size of the two lumps and analysis of the images was used to propose a diagnosis of FA. Therefore, a lumpectomy was performed. Analysis of the frozen section indicated a diagnosis of FA in the right breast, however, a 5-mm LCIS was identified within the FA of the left breast. Subsequent to the identification of three additional lumps in the left breast, a left mastectomy was performed. During a five-year follow-up period, no local recurrence or contralateral breast carcinoma occurred. The present study showed that FAs containing foci of carcinoma in situ can be indistinguishable from benign lesions following imaging, therefore, despite the incidence of carcinoma within FA is estimated at 0.1-0.3%, it should be considered a long-term risk factor for invasive breast cancer. The present describes a case of LCIS arising within an FA and conducts a review of the relevant literature.