This colorectal carcinoma has a medullary growth pattern and is chock full of lymphocytes. There is loss of immunohistochemical staining for MLH1 protein in the malignant nuclei (staining is retained in the lymphocytes). Such tumors are more likely to respond to immunotherapy than neoplasms without the illustrated features.
Case provided by Dr. Elizabeth Montgomery, Professor of Pathology and Vice Chair of Anatomic Pathology at the University of Miami, and Editor-In-Chief at Innovative Science Press. Check out our new titles at: