Figure 1. False-Positive Tumor Due to Rare Microsatellite Polymorphisms: Immunohistochemistry.

Immunohistochemistry of tumor sections from patient 47 using antibodies targeting MLH1, PMS2, MSH2, and MSH6 showing the expression of all 4 mismatch repair proteins in tumor cells (ie, mismatch repair proficiency), and hematoxylin-eosin stain of a tumor section.