Metastatic Breast Carcinoma to the Prostate Gland

Figure 1

Breast core biopsy shows infiltrative nests of epithelioid cells with small ovoid hyperchromatic nuclei and modest eosinophilic cytoplasm separated by fibrous stroma with a desmoplastic reaction on H&E. Immunohistochemical stains show nuclear staining for ER and negative staining for PR and CK5/6.