PRDM5 immunohistochemistry. A demonstrates the normal pattern of staining in non-neoplastic colonic mucosa. Down arrows indicate strong nuclear and cytoplasmic staining for PRDM5 in scattered cells predominantly in the crypt bases. Up arrowheads indicate incidental melanosis coli in the lamina propria. B is a representative area of a colorectal carcinoma negative for PRDM5. C is a representative area of a colorectal carcinoma positive for PRDM5, showing scattered cells with strong cytoplasmic and/or nuclear staining. (Original magnification: x200).