title: Expression of TTF-1 in breast cancer independently of ER expression: A case report and pathogenic implications.
abstract: Thyroid Transcription Factor 1 (TTF-1) is often used for the immunohistochemical evaluation of lung cancers, as a significant proportion of these cancers are positive while other adenocarcinomas are usually negative. Breast cancers are known to express TTF-1 only in a small minority of cases but this may be problematic when this staining is used for its differential diagnosis from lung cancer. We present a case of ER-positive breast cancer in 30% of tumor cells that was also TTF-1 positive in some areas of the primary tumor but lost ER expression completely in the metastatic recurrence site while retaining TTF-1 positivity. Additionally, a PTEN mutation was present on genomic evaluation of the primary tumor. Diagnostic, pathogenic and therapeutic implications of these findings are discussed.
authors.affiliation: Division of Medical Oncology, Department of Internal Medicine, Sault Area Hospital, Sault Ste Marie, ON, Canada.|Division of Clinical Sciences, Northern Ontario School of Medicine, Sudbury, ON, Canada.
authors.forename: Ioannis A
authors.initials: IA
authors.lastname: Voutsadakis
authors.affiliation: Department of Pathology, Sault Area Hospital, Sault Ste Marie, ON, Canada.
authors.forename: Paul
authors.initials: P
authors.lastname: Mozarowski
mesh_terms: D001365:Axilla; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology* / Q000628:therapy; D018270:Carcinoma, Ductal, Breast / Q000235:genetics / Q000378:metabolism* / Q000556:secondary* / Q000628:therapy; D059186:Chemoradiotherapy, Adjuvant; D017809:Fatal Outcome; D005260:Female; D050990:GATA3 Transcription Factor / Q000378:metabolism; D006801:Humans; D008197:Lymph Node Excision; D008408:Mastectomy; D008875:Middle Aged; D009362:Neoplasm Metastasis; D051059:PTEN Phosphohydrolase / Q000235:genetics; D011960:Receptors, Estrogen / Q000378:metabolism; D000074482:Thyroid Nuclear Factor 1 / Q000378:metabolism*
chemical_list: D050990:GATA3 Transcription Factor; C494749:GATA3 protein, human; D011960:Receptors, Estrogen; D000074482:Thyroid Nuclear Factor 1; D051059:PTEN Phosphohydrolase; C494929:PTEN protein, human
keywords: Breast cancer; Estrogen Receptor; PTEN mutation; TTF-1; diagnosis