PGR and ductal breast carcinoma in situ: The staging of invasive SPC is determined by the size of the invasive component, with Nottingham grading and estrogen and progesterone receptor and HER2/neu studies performed on the invasive tumor component [1,2,7]. Immunohistochemistry can be useful in the diagnosis and analysis of SPCs. Approximately 50% of SPCs are immunopositive for neuroendocrine markers, such as chromogranin and synaptophysin, reactivities that are rare in DCIS and florid ductal hyperplasia.