KRT7 and neoplasm: Several ‘mesothelial markers’ including calretinin, D2-40/podoplanin, WT1 and cytokeratin (CK) 5/6 are used routinely in diagnostic histopathology practice, but in our experience CK7 staining is often most useful in this context since it labels mesothelial cells strongly whereas reactive stromal elements and tumor cells in the majority of CRC are negative.