Ectopic breast tissue as a possible cause of false-positive axillary sentinel lymph node biopsies

Eugenio Maiorano, Giovanni M. Mazzarol, Giancarlo Pruneri, Mauro G. Mastropasqua, Stefano Zurrida, Enrico Orvieto, Giuseppe Viale

Research output: Contribution to journalArticlepeer-review


Epithelial inclusions representing ectopic breast tissue are uncommonly seen in axillary lymph nodes. The extensive histopathologic examination of axillary sentinel lymph nodes of patients with breast carcinoma may increase the chances to encounter tiny foci of ectopic breast tissue, which may be misinterpreted as (micro)metastatic disease and lead to unwarranted completion of axillary dissection and to inaccurate staging and improper adjuvant treatments for the patients. Here we report on seven cases of ectopic breast tissue in axillary sentinel lymph nodes. In three cases there were coexistent micrometastases, and in the remaining cases the ectopic tissue was not associated with metastatic disease. The ectopic breast tissue showed remarkably varied morphologic features, including apocrine metaplasia and proliferative changes indistinguishable from those occurring in sclerosing adenosis and florid epithelial hyperplasia of the breast. A peripheral layer of myoepithelial cells was consistently detected in the ectopic glands and ducts. Besides awareness and purely morphologic criteria, a false-positive identification of these inclusions as metastatic carcinoma may be avoided by the use of immunohistochemical reactions for the localization of specific markers of the myoepithelial cell component, which is associated with the ectopic breast tissue.

Original languageEnglish
Pages (from-to)513-518
Number of pages6
JournalAmerican Journal of Surgical Pathology
Issue number4
Publication statusPublished - Apr 1 2003


  • Axillary sentinel lymph node
  • Breast carcinoma
  • Ectopic breast tissue
  • Epithelial inclusions

ASJC Scopus subject areas

  • Anatomy
  • Pathology and Forensic Medicine


Dive into the research topics of 'Ectopic breast tissue as a possible cause of false-positive axillary sentinel lymph node biopsies'. Together they form a unique fingerprint.

Cite this