Why is LCIS Important—Pathological Review

Purpose of Review
Lobular carcinoma in situ (LCIS) encompasses classical LCIS and other rarer and more recently recognised variants, namely pleomorphic LCIS (PLCIS) and florid LCIS. Each of those entities has characteristic histological diagnostic criteria, different rates of underestimation of malignancy and recommended management. In addition, those lesions can mimic a number of benign and malignant breast lesions and can particularly be mistaken for ductal carcinoma in situ (DCIS). Accurate diagnosis of those lesions is critical to ensuring the appropriate patient management.

Recent Findings
Several international guidelines refining the pathological classification, staging and management of those lesions have recently been updated. This review will provide an up-to-date pathological overview of the current knowledge of LCIS with emphasis on the multidisciplinary management implications.

Summary
Close correlation between imaging and pathology in a multidisciplinary pathway is essential in LCIS management. Classical LCIS on core biopsy/vacuum-assisted biopsy (VAB) is coded as B3 and, if without discordant imaging, should further be sampled by vacuum-assisted excision (VAE). PLCIS should be coded and managed as per high-grade DCIS. Florid LCIS is a rare entity that is thought to be more aggressive than classical LCIS. Excision with clear margin is advised.