Immunohistochemical detection of HCMV in normal breast and breast cancer. (a, b) Examples of HCMV IE immuonreactivity in isolated area of normal ductal epithelium in normal breast from a reduction mammoplasty patient are presented. Low (a, 40×) and higher (b, 100×) power views of the same area of immunoreactive epithelium demonstrate discrete perinuclear and cytoplasmic epithelial cell staining. No IE immunoreactivity is detected in two different specimens obtained from normal reduction mammoplasty (c and d, 40×; e is 100× magnification of d). IE immunoreactivity is demonstrated primarily in a nuclear distribution in matched non-neoplastic epithelium from a patient with infiltrative ductal carcinoma (f, 100×). Early and late (E/L) immunoreactivity is demonstrated in the tumor epithelial cells, but not the stroma, from an area of ductal carcinoma in situ (DCIS) in a patient with infiltrative ductal carcinoma (g, 40×, h, 100×). Positive control immunostaining for IE immunoreactivity is shown in HCMV infected pneumocytes from an AIDS patient with CMV pneumonia (i, 100×). Late antigen (L) immunoreactivity is shown in another patient with infiltrative ductal carcinoma (j, 40×; k, 100×). Negative control (IE isotype control antibody staining for CD34) immunoreactivity is seen only in vascular endothelial cells in an area of infiltrative ductal carcinoma (l, 40×).