title: Squamous cell carcinoma in situ of the breast: a light microscopic and immunohistochemical study of a previously undescribed lesion.
abstract: Three cases of squamous carcinoma in situ of the breast, one with an invasive component are described in women aged 35, 51, and 59 years. Two cases were detected by screening mammography. In 1 case, the squamous ductal carcinoma in situ was extensive. All cases showed obvious squamous features on standard hematoxylin and eosin sections. The in situ component of the lesions and the squamous differentiation were supported by immunohistochemistry. In 2 cases, the neoplastic cells showed actin positivity indicating myoepithelial cell differentiation. One case showed trilineage differentiation into luminal, squamous, and myoepithelial cells. These cases illustrate a variant of duct carcinoma in situ that has not been described in the current literature and provide insights into the dual epithelial-myoepithelial differentiation of some breast neoplasms.
authors.affiliation: Department of Pathology, BC Cancer Agency, Vancouver, Canada
authors.forename: Malcolm M
authors.initials: MM
authors.lastname: Hayes
authors.forename: Johannes L
authors.initials: JL
authors.lastname: Peterse
authors.forename: Ekrem
authors.initials: E
authors.lastname: Yavuz
authors.forename: Gisela H
authors.initials: GH
authors.lastname: Vischer
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Eusebi
mesh_terms: D000328:Adult; D014408:Biomarkers, Tumor / Q000032:analysis*; D001943:Breast Neoplasms / Q000737:chemistry / Q000175:diagnosis / Q000473:pathology*; D002285:Carcinoma, Intraductal, Noninfiltrating / Q000737:chemistry / Q000175:diagnosis / Q000473:pathology*; D002294:Carcinoma, Squamous Cell / Q000737:chemistry / Q000175:diagnosis / Q000473:pathology*; D002454:Cell Differentiation; D019070:Cell Lineage; D004847:Epithelial Cells / Q000473:pathology; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008327:Mammography; D008853:Microscopy; D008875:Middle Aged; D009208:Myoepithelioma / Q000737:chemistry / Q000175:diagnosis / Q000473:pathology*; D009361:Neoplasm Invasiveness
chemical_list: D014408:Biomarkers, Tumor