8520/2 LCIS, NOS


ICD-O-3 topography code: C50

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.

Classic LCIS is diagnosed when more than half of the acini of a lobular unit are distended and distorted by a dyshesive proliferation of cells with small, uniform nuclei.

See Lobular neoplasia for detailed discussion.