Pathology Notes

MUTYH-associated polyposis   Updated: 03/02/2021 © Jun Wang, MD, PhD General features AKA MYH-associated polyposis Autosomal recessive Considered a mild form of familial adenomatous polyposis Biallelic mutation of MUTYH gene (DNA mismatch repair) Less 1% of patients with colorectal cancer Pathogenesis MUTYH mutation results in mutation of other genes , including APC and KRAS Clinical presentations Multiple colon polyps , usually less than 100, by age 50 to 60 Extracolonic presentations Polyps may be seen in other organs, such as stomach and small intestine Osteoma Sebaceous hyperplasia or adenoma , etc Pathological features Primarily adenoma Severe dysplasia at early age Genetic abnormalities MUTYH Diagnosis Suspicious presentations Cumulative 10 or more colorectal adenomas Colorectal adenoma with extracolic features of FAP Genetic testing for MYH Back to intestinal tumors Back to syndromes Back to contents

Serrated Polyposis Syndrome Updated: 02/28/2022 © Jun Wang, MD, PhD   General features Previously called hyperplastic polyposis syndrome More common age 50-60 Increased risk for colon rectal cancer Associated with cigarettes smoking and high BMI Increased risk of colorectal cancer Clinical presentations Usually asymptomatic Endoscopic findings of large or flat polyps Key morphological features Both adenomatous and hyperplasic changes Genetic abnormalities Overall uncommon BRAF: Type1, commonly female smokers KRAS: Type 2, RNF43 Diagnostic criteria More than 5 serrated polyps proximal to the sigmoid colon, at least 2 of these are larger than 1 cm Any serrated polyps proximal to the sigmoid colon in a patient with a first degree relative with serrated polyposis syndrome More than 20 serrated polyps of any size in the colon Treatment Polypectomy, complete removal recommended Colonoscopy every 1-3 years Surgery if treatment/surveillance inadequate First degr

Pathology of intestinal tumors   Updated: 03/02/2021 © Jun Wang, MD, PhD Key anatomy and histology Jejunum: Villi Ileum: villi, more goblet cells, Peyer’s patch Colon: Crypts, no villi Polyps Hyperplastic polyp Inflammatory polyp Juvenile polyp Peutz-Jegher polyp/syndrome Adenomatous polyp Sessile serrated adenoma Syndromes with GI polyp/malignancy Familial adenomatous polyposis Gardner syndrome MYH-associated polyposis Genetic abnormalities of intestinal polyp/tumor Adenocarcinoma Carcinomas of anal canal Tumors of appendix Practice questions A Practice questions B Back to contents

Peutz-Jeghers syndrome   Updated: 01/10/2023 © Jun Wang, MD, PhD General features Autosomal dominant with variable penetrance, usually diagnosed in 20’s Markedly increased risk of malignancies of different organs, including gastric type adenocarcinoma of cervix May have Sertoli cell tumor of ovary Genetic abnormalities STK-11 Diagnostic criteria 3+ histologically confirmed Peutz-Jeghers polyps Any Peutz-Jeghers polyp with a family history Characteristic melanotic mucocutaneous pigmentation (lips, oral mucosa, genitalia, digits, palms and soles) with a family history Peutz-Jegher polyp and characteristic mucocutaneous pigmentation Peutz-Jeghers polyp Broad bands of smooth muscle fibers , thicker centrally, with “Christmas tree” appearance Relatively normal glands Back to intestinal tumors Back to syndromes Back to contents