title: Primary small cell carcinoma of the breast with TTF-1 and neuroendocrine marker expressing carcinoma in situ.
abstract: Primary small cell carcinoma (SmCC) of the breast is very rare and may be difficult to distinguish from metastatic small cell carcinoma. Confident histopathological diagnosis of a primary breast SmCC requires the demonstration of an in situ component. We report a case of primary small cell carcinoma of the breast with coexisting carcinoma in situ in which the invasive carcinoma and in situ component both expressed neuroendocrine markers and Thyroid transcription factor-1 (TTF-1) by immunohistochemistry. Expression of neuroendocrine markers and TTF-1 in the in situ component allowed a highly confident diagnosis of primary small cell carcinoma of the breast. To our knowledge there is only one previous report of TTF-1 expressing in situ carcinoma associated with a primary SmCC of the breast.
authors.affiliation: Department of Anatomical Pathology, Royal Melbourne Hospital, Parkville, Victoria, Australia. Michael.christie@mh.org.au
authors.forename: Michael
authors.initials: M
authors.lastname: Christie
authors.forename: Laura
authors.initials: L
authors.lastname: Chin-Lenn
authors.forename: Monique M
authors.initials: MM
authors.lastname: Watts
authors.forename: Alpha E
authors.initials: AE
authors.lastname: Tsui
authors.forename: Malcolm R
authors.initials: MR
authors.lastname: Buchanan
mesh_terms: D014408:Biomarkers, Tumor / Q000032:analysis*; D001943:Breast Neoplasms / Q000378:metabolism / Q000473:pathology*; D002278:Carcinoma in Situ / Q000378:metabolism / Q000473:pathology*; D018288:Carcinoma, Small Cell / Q000378:metabolism / Q000473:pathology*; D004893:Erythema Nodosum / Q000150:complications; D017809:Fatal Outcome; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008875:Middle Aged; D009687:Nuclear Proteins / Q000096:biosynthesis*; D010996:Pleural Effusion / Q000150:complications; D049268:Positron-Emission Tomography; D000074482:Thyroid Nuclear Factor 1; D014057:Tomography, X-Ray Computed; D014157:Transcription Factors / Q000096:biosynthesis*
chemical_list: D014408:Biomarkers, Tumor; C000614412:NKX2-1 protein, human; D009687:Nuclear Proteins; D000074482:Thyroid Nuclear Factor 1; D014157:Transcription Factors