title: Metaplastic carcinoma of the breast: multimodality imaging and histopathologic assessment.
abstract: BACKGROUND
  Metaplastic carcinomas are ductal carcinomas that display metaplastic transformation of the glandular epithelium to non-glandular mesenchymal tissue. Metaplastic carcinoma has a poorer prognosis than most other breast cancers, so the differential diagnosis is important. Although many clinical and pathologic findings have been reported, to our knowledge, few imaging findings related to metaplastic carcinoma have been reported.
  
  
  OBJECTIVE
  To investigate whole-breast imaging findings, including mammography, sonography, MRI, and pathologic findings, including immunohistochemical studies of metaplastic carcinomas of the breast.
  
  
  METHODS
  We analyzed 33 cases of metaplastic carcinoma between January 2001 and January 2011. Mammography, ultrasonography, and MRI were recorded retrospectively using the American College of Radiology (ACR) breast imaging reporting and data system (BI-RADS) lexicon. Immunohistochemical studies of estrogen receptor (ER), progesterone receptor (PR), p53, and C-erbB-2 were performed.
  
  
  RESULTS
  The most common mammographic findings were oval shape (37%), circumscribed margin (59%), and high density (74%). The most common sonographic findings were irregular shape (59.4%), microlobulated margin (41%), complex echogenicity (81%), parallel orientation (97%), and posterior acoustic enhancement (50%). Axillary lymph node metastases were noted for 25% of the sonographic examinations. On MRI, the most common findings of margin and shape were irregularity (57% and 52.4%, respectively). High signal intensity was the most common finding on T2-weighted images (57%). Immunohistochemical profile was negative for ER (91%, 29/32) and PR (81%, 26/32).
  
  
  CONCLUSIONS
  Metaplastic carcinomas might display more benign features and less axillary lymph node metastasis than IDC. High signal intensity on T2 MRI images and hormone receptor negativity would be helpful in differentiating this tumor from other breast cancers.
authors.affiliation: Department of Radiology, Chungnam National University Hospital, Daejeon, Korea. med20@hanmail.net
authors.forename: Bo Bae
authors.initials: BB
authors.lastname: Choi
authors.forename: Kwang Sun
authors.initials: KS
authors.lastname: Shu
mesh_terms: D000328:Adult; D000368:Aged; D001940:Breast / Q000473:pathology / Q000648:ultrastructure; D001943:Breast Neoplasms / Q000175:diagnosis* / Q000648:ultrastructure; D018270:Carcinoma, Ductal, Breast / Q000175:diagnosis* / Q000556:secondary* / Q000648:ultrastructure; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008207:Lymphatic Metastasis; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008327:Mammography / Q000379:methods*; D008679:Metaplasia; D008875:Middle Aged; D015203:Reproducibility of Results; D012189:Retrospective Studies; D016217:Ultrasonography, Mammary / Q000379:methods*