title: Solitary metastasis to the breast after complete resection of encapsulated type AB thymoma: a case report.
abstract: BACKGROUND
  Type AB thymoma is generally considered a benign tumor with excellent prognosis. Rare case reports of type A and AB thymomas with recurrence and metastasis have been documented, although extrathoracic metastases are extremely rare. To the best of our knowledge, this is the first reported case of type AB thymoma with solitary metastasis to the breast.
  
  
  METHODS
  We describe an 83-year-old Taiwanese woman with a metastatic thymoma to the breast 10 years after complete resection of noninvasive and encapsulated primary tumor, and analyze the possible factors to explain the recurrence and metastasis of the stage I thymomas.
  
  
  CONCLUSIONS
  Even a clinically benign tumor such as type AB thymoma still has a possibility of metastasizing to an unusual site. When any uncommon tumor presents in any site, a suspicion of secondary neoplasm and thorough clinical history are required.
authors.affiliation: Department of Pathology, Mackay Memorial Hospital, Hsinchu, No.690, Sec. 2, Guangfu Rd, East Dist, Hsinchu City, 30071, Taiwan. hiruaa@yahoo.com.tw.
authors.forename: Pei-Wen
authors.initials: PW
authors.lastname: Huang
authors.affiliation: Department of Pathology, Mackay Memorial Hospital, Hsinchu, No.690, Sec. 2, Guangfu Rd, East Dist, Hsinchu City, 30071, Taiwan. a5523@ms7.mmh.org.tw.
authors.forename: Kuo-Ming
authors.initials: KM
authors.lastname: Chang
mesh_terms: D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000473:pathology / Q000556:secondary*; D005260:Female; D006801:Humans; D009364:Neoplasm Recurrence, Local; D013945:Thymoma / Q000473:pathology / Q000556:secondary* / Q000601:surgery; D013953:Thymus Neoplasms / Q000473:pathology* / Q000601:surgery