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WHO Classification of Tumours
Lobular carcinoma in situ, NOS


Lobular carcinoma in situ (LCIS) is a non-invasive adenocarcinoma of the breast originating in the terminal duct lobular unit (TDLU). It is characterized by a proliferation of generally small, loosely cohesive monomorphic cells which replace or displace the normal epithelial cells in the TDLU. The overall lobular architecture is preserved. Mitotic activity is low. Necrosis and calcification are uncommon. LCIS is frequently multicentric (approximately 85% of cases) and bilateral.
A majority of LCIS are estrogen- and progesterone-receptor positive. The tumours generally lack E-cadherin.
Lobular carcinoma in situ occurs in women from 15 to 90 years of age, but most patients are premenopausal. Patients with LCIS carry an increased risk of developing invasive ductal or invasive lobular carcinoma . Lifelong follow-up is therefore recommended

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Tavassoli FA, Devilee P (Eds.)
World Health Organization Classification of Tumours. Pathology and Genetics of Tumours of the Breast and Female Genital Organs.
3rd Edition
IARC Press: Lyon 2003