Metaplastic Breast Carcinoma: Update on Histopathology and Molecular Alterations

Arch Pathol Lab Med. 2019 Dec;143(12):1492-1496. doi: 10.5858/arpa.2019-0396-RA.


Context—: Metaplastic carcinoma is a rare, triple-negative carcinoma of the breast that exhibits transformation of part or all of its glandular carcinomatous component into a nonglandular, or metaplastic, component. The World Health Organization currently recognizes 5 variants of metaplastic carcinoma based on their histologic appearance.

Objective—: To review the histologic classifications, differential diagnosis, prognosis, and recent laboratory studies of metaplastic breast carcinoma.

Data sources.—: We reviewed recently published studies that collectively examine metaplastic carcinomas, including results from our own research.

Conclusions.—: Metaplastic breast carcinoma has a broad spectrum of histologic patterns, often leading to a broad differential diagnosis. Diagnosis can typically be rendered by a combination of morphology and immunohistochemical staining for high-molecular-weight cytokeratins and p63. Recent studies elucidate new genes and pathways involved in the pathogenesis of metaplastic carcinoma, including the downregulation of CCN6 and WNT pathway gene mutations, and provide a novel MMTV-Cre;Ccn6fl/fl knockout disease-relevant mouse model to test new therapies.

Publication types

  • Review

MeSH terms

  • Animals
  • Biomarkers, Tumor / analysis
  • Female
  • Humans
  • Metaplasia / diagnosis
  • Metaplasia / genetics
  • Metaplasia / pathology
  • Triple Negative Breast Neoplasms / diagnosis
  • Triple Negative Breast Neoplasms / genetics*
  • Triple Negative Breast Neoplasms / pathology*


  • Biomarkers, Tumor