Genetics Cells of Lobular Neoplasia (LN), including both Atypical Lobular Hyperplasia and<unk> , and ILC share common genetic alterations, perhaps accounting, in part, for the similarities in histologic appearance. Classic<unk>  and invasive lobular lesions are low-grade ER and PR-positive cancers, referring to the positive expression of Estrogen and Progesterone receptors on the neoplastic cells (determined via immunohistochemistry). These entities are also both classically negative for HER2 (human epidermal growth factor receptor 2). These hormone and growth factor receptors are clinically significant, as they represent targets for chemotherapy. Chromosomal alterations have also been consistently observed between<unk>  and ILC – namely, loss of 16q and gain of 1q, referring to the loss of the long arm (designated q) of chromosome 16 and an extra copy of the long arm of chromosome 1. Furthermore, e-cadherin, the transmembrane protein mediating epithelial cell adhesion, exhibits loss of expression on LN cells, and P120 Catenin exhibits cytoplasmic reactivity. The mechanism for these findings is explained by E-cadherin normally interacting with p120 catenin in the cytoplasm. When e-cadherin is lost, p120 cadherin builds up in the cytoplasm of the neoplastic cells – thus, producing a positive reaction in immunohistochemical testing.<unk>  often have the same genetic alterations (such as loss of heterozygosity on chromosome 16q, the locus for the e-cadherin gene) as the adjacent area of invasive carcinoma. These observations, along with genomic analysis for clonal relationships between the cells of<unk>  and ILC, support<unk>  as being a precursor to ILC, and that the lesions encompassed by the broader category of Lobular Neoplasia (LN) fall on a linear spectrum of progression.<unk>  is often found concurrently with foci of invasive carcinoma and multiple studies have shown, using genetic sequencing techniques, that synchronous<unk>  and ILC share clonal cell populations, or originate from the same line of mutated cells.
Lobular carcinoma in situ
Ductal carcinoma in situ
Sister Mary Joseph nodule
Invasive lobular carcinoma
Invasive carcinoma of no special type
Lymphoepithelioma-like carcinoma
Focal nodular hyperplasia
Atypical ductal hyperplasia