Lobular neoplasia (LN) is a risk factor for bilateral breast cancer without consensus as to its appropriate management. The authors report on a retrospective multi-institutional study concerning 52 patients in whom a diagnosis of LN was made after core needle biopsy (CNB) and who subsequently underwent surgical excision. The excision specimens revealed seven cases of invasive carcinoma and three cases of ductal carcinoma in situ, indicating an underestimation of lesions at CNB in 19% of cases, and in particular in those patients with pleomorphic LN, and when clinical, radiological masses were detected. This lesion is increasingly being diagnosed by CNB due to widespread screening. Follow-up surgical excision should be performed in order to examine the whole lesion in the case of masses or when the histologic specimen reveals a pleomorphic subtype. In other cases, annual mammographic surveillance should be undertaken due to the persistent long-term risk of developing bilateral breast cancer.