title: Gastrointestinal metastasis to the breast.
abstract: BACKGROUND
  Although primary breast cancer is common, metastatic disease to the breast, especially primary gastrointestinal cancer, is rare. Routine pathologic examination may be helpful in determining the true diagnosis, but can be misleading.
  
  
  METHODS
  To determine whether a signet ring carcinoma was a primary malignancy of the gastrointestinal tract metastatic to the breast or vice versa, histochemical analysis was performed for Her-2/NEU, gross cystic disease fluid protein-15, estrogen receptor, progesterone, carcinoembryonic antigen, cytokeratin 7, and cytokeratin 20.
  
  
  RESULTS
  Positive staining for carcinoembryonic antigen and cytokeratin 20 (and negative staining for the breast cancer antigens), and the clinical criteria favors the diagnosis of gastrointestinal carcinoma metastatic to the mammary gland.
  
  
  CONCLUSIONS
  Because the prognosis of therapy for metastatic cancer to the breast differs from that of primary breast cancer, it is imperative that the correct diagnosis be established. Immunohistochemistry for carcinoembryonic antigen and cytokeratin 20 are particularly useful. Metastatic gastrointestinal carcinoma to the breast is a rare lesion but needs to be at least included in the differential diagnosis of breast masses, especially in patients with a history of gastrointestinal cancer.
authors.affiliation: Department of Surgery, Tulane University School of Medicine, and Department of Pathology, Louisiana State University Medical Center, New Orleans, LA 70112, USA.
authors.forename: Atul K
authors.initials: AK
authors.lastname: Madan
authors.forename: Craig
authors.initials: C
authors.lastname: Ternovits
authors.forename: Samantha A
authors.initials: SA
authors.lastname: Huber
authors.forename: Leo A
authors.initials: LA
authors.lastname: Pei
authors.forename: Bernard M
authors.initials: BM
authors.lastname: Jaffe
mesh_terms: D000328:Adult; D001943:Breast Neoplasms / Q000378:metabolism / Q000473:pathology* / Q000556:secondary*; D002272:Carcinoembryonic Antigen / Q000378:metabolism; D018279:Carcinoma, Signet Ring Cell / Q000378:metabolism / Q000473:pathology* / Q000556:secondary*; D003937:Diagnosis, Differential; D005260:Female; D005770:Gastrointestinal Neoplasms / Q000473:pathology*; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D007381:Intermediate Filament Proteins / Q000378:metabolism; D053554:Keratin-20; D013194:Staining and Labeling
chemical_list: D002272:Carcinoembryonic Antigen; D007381:Intermediate Filament Proteins; C507499:KRT20 protein, human; D053554:Keratin-20