title: Nested and microcystic variants of urothelial carcinoma displaying immunohistochemical features of basal-like urothelial cells: an immunohistochemical and histopathogenetic study.
abstract: Nested/microcystic (NV/MV) urothelial carcinoma (UC) variants are associated with mild cytologic atypia and commonly present at high-stage disease. The histopathogenesis is investigated using urothelial basal cell markers. Archival 14 NV/MV and three inverted papilloma (IP) were immunostained for CD44, cytokeratin 5 (CK5), CK34bE12 and p63. Twenty consecutive cases of invasive high-grade UC including 14 superficial and 6 muscle-invasive UC cases were used as control. Immunostaining was scored as high for staining of full or more than 50% thickness of the epithelial nest or epithelium and low for lesser immunoreactivity and negative reactivity. All 14 NV/MV, 3 IP and 6 control cases showed a high score of immunoreactivity for CK5, CD44, CK34bE12 and focally for p63. The remaining control cases showed a high score of immunoreactivity for CK34bE12, while negative or low for CK5, CD44 and p63. In conclusion, immunoreactivity CK5 and CD44 commonly immunostained NV/MV and some invasive high grade UC. Other basal cell markers (CK34bE12 and p63) appear to be non specific or non sensitive. NV and MV and some UC likely represent a subset of UC displaying immunohistochemical features of urothelial basal cells. They had tendency of endophytic growth and early invasion despite the innocuous cytologic appearance.
authors.affiliation: Pathology and Laboratory Medicine, The Ottawa Hospital and University of Ottawa, Ottawa, Ontario, Canada.
authors.forename: Kien T
authors.initials: KT
authors.lastname: Mai
authors.forename: Shaheed W
authors.initials: SW
authors.lastname: Hakim
authors.forename: Christopher G
authors.initials: CG
authors.lastname: Ball
authors.forename: Trevor A
authors.initials: TA
authors.lastname: Flood
authors.forename: Eric C
authors.initials: EC
authors.lastname: Belanger
mesh_terms: D000368:Aged; D014408:Biomarkers, Tumor / Q000378:metabolism*; D002295:Carcinoma, Transitional Cell / Q000378:metabolism* / Q000473:pathology; D004847:Epithelial Cells / Q000473:pathology; D005260:Female; D006801:Humans; D018960:Hyaluronan Receptors / Q000378:metabolism*; D007150:Immunohistochemistry; D053555:Keratin-5 / Q000378:metabolism*; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism; D008875:Middle Aged; D001749:Urinary Bladder Neoplasms / Q000378:metabolism* / Q000473:pathology; D019459:Urothelium / Q000378:metabolism* / Q000473:pathology
chemical_list: D014408:Biomarkers, Tumor; C497483:CD44 protein, human; C081876:CKAP4 protein, human; D018960:Hyaluronan Receptors; D053555:Keratin-5; D008565:Membrane Proteins
keywords: basal; inverted; microcystic; nested; urothelial