Metaplastic carcinoma of the breast: Imaging and pathological features.

Metaplastic carcinoma of the breast is a rare form of breast cancer. The aim of the present study was to investigate the imaging and pathological features of metaplastic carcinoma. The features identified on mammography and sonography were retrospectively reviewed in 13 women with metaplastic carcinoma of the breast. The results from the mammographs and sonographs were additionally evaluated using immunohistochemical staining for the expression of the estrogen receptor (ER) and progesterone receptor (PR), receptor tyrosine-protein kinase erbB-2 (CerbB-2) and P53. The most common features observed in the mammographs were as follows: Irregular and oval shaped masses, 53.8 and 46.2%, respectively; spiculated and circumscribed margins, each 30.8%; and high and marginally high density masses, 69.2 and 30.8%, respectively. The most common sonography features observed were as follows: Hypoechoic masses, 84.6%; complex echogenicity, 76.9%; irregular, round and oval shaped masses, 69.2, 30.8 and 30.8%, respectively; indistinct and circumscribed margins, 53.8 and 46.2%, respectively; an abundant blood flow, 53.8%; and posterior acoustic enhancement, 61.5%. The immunohistochemical (IHC) profile for 13 patients demonstrated that ER was not expressed in 100% of patients, PR and CerbB-2 were not present in 92.3% of patients, and P53 was present in 63.6% of patients. Therefore, metaplastic carcinoma of the breast exhibits more benign IHC features compared with invasive ductal carcinoma. In addition, it may be challenging to diagnose patients that do not possess posterior acoustic enhancement or express hormone receptors from other types of breast cancer.