Lobular intraepithelial neoplasia arising within breast fibroadenoma

Background Fibroadenomas are the second most common breast pathology occurring in young women under the age of 35 years old. Fibroadenomas can be classified as simple or complex according to histological features. Complex fibroadenomas differ from simple fibroadenomas because of the presence of cysts (3 mm), sclerosing adenosis, epithelial calcifications, or papillary apocrine changes. Most fibroadenomas are clinically identifiable. In 25% of cases, fibroadenomas are non-palpable and are diagnosed with mammography and ultrasound. Differential diagnosis with well differentiated breast cancer is often necessary, particularly with medullary or mucinous tumors. Calcification findings within fibroadenomas by mammogram have to be investigated. The age of a lump is usually reflected by calcifications. Microcalcification can hide foci of carcinoma in situ when they are small, branching type, and heterogeneous. However, many morphological possibilities may not be reliable for deciding whether a certain calcification is the product of a malignant or a benign process. From a radiological point of view, fibroadenomas containing foci of carcinoma in situ can be indistinguishable from benign lesions, even if the incidence of carcinoma within fibroadenomas is estimated as 0.1–0.3%, and it could be a long-term risk factor for invasive breast cancer.