44-year-old woman with left-sided breast mass   

History and images

Our appreciation is extended to Dr. Abdul Abid, University of Texas Medical Branch, for contributing this case.

History: A 44-year-old woman presented with a left-sided breast mass. There was no history of trauma or family history of breast cancer. A diagnostic mammogram revealed an irregular mass measuring at least 29 mm at the 2 o'clock position and 8 cm from the nipple. The mass was assigned a BI-RADS category 5. Biopsies were obtained for a histological examination.

Click the images to enlarge.

What is the most likely diagnosis?
Nodular fasciitis
Invasive lobular carcinoma
Low-grade metaplastic carcinoma

Which immunohistochemical stains would help with the diagnosis?
CD34 +ve, CK +ve
CD34 +ve, ER +ve
CD34 -ve, beta-catenin +ve
CD34 +ve, SMA +ve