Purpose:According to the American Joint Committee on Cancer’s 8th Edition Manual, lobular carcinoma in situ (LCIS) is no longer considered a malignant disease, although it may be a precursor to the development of breast cancer. The present study aimed to evaluate the clinicopathological features and prognosis of LCIS.

Methods:This study retrospectively analyzed clinicopathological features and prognosis data of LCIS among patients who underwent breast surgery at Severance Hospital, Seoul, South Korea from 1991 to 2016.

Results:Of the 47 patients, 49 cases of LCIS were confirmed by postoperative pathology. The mean patient age was 48.15±8.34 years. Most patients (81.6%) did not have palpable tumors at diagnosis, and 51.0% showed no microcalcification on mammography. Breast-conserving surgery was performed more frequently than total mastectomy (77.6% vs. 22.4%). The mean tumor size was 1.63±2.11 cm. There were only 3 cases of pleomorphic LCIS. Hormone receptor-positive tumors were noted in 47 cases, however, the hormone receptor status was unknown in the other 2 cases. There were no LCIS recurrences or deaths during the follow-up period (mean 56 months).

Conclusion:LCIS is often incidentally diagnosed without clinical symptoms, especially in women aged <50 years. The prognosis of LCIS is excellent in cases that are surgically treated.