KRT20 and adenocarcinoma: In contrast with the prostate biopsy, bone marrow aspiration and biopsy demonstrated marrow packed with poorly differentiated adenocarcinoma with signet ring cells showing positive immunohistochemical staining for keratin 7 (krt7) and prolactin-induced protein (pip: Figure 1), and also carcinoembryonic antigen (cea), but without staining for prostate-specific antigen, prostate-specific acid phosphatase, P504S, CD45, keratin 20 (krt20), vimentin, TTF1, CDX2, S100, or estrogen receptors.