Pathology and Immunohistochemistry of Hereditary Colorectal Cancer

Hereditary colorectal adenocarcinomas only represent a small proportion of all colorectal cancers and, of those, only a fraction have distinct clinical or pathologic features and a mutation of a gene associated with a hereditary syndrome. These hereditary conditions include hereditary nonpolyposis colorectal cancer, familial adenomatous polyposis, MUTYH-associated polyposis, Peutz–Jeghers syndrome, and juvenile polyposis syndrome. Histopathologic features in patients with colorectal lesions (polyps, adenocarcinoma) that suggest the presence of a hereditary condition include the number and type of polyps, the morphologic features of the colorectal carcinoma, and the presence of extracolonic lesions or tumors. In addition, immunohistochemical stains can assist in identifying patients with hereditary nonpolyposis colorectal cancer.