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

Practice question answers, intestinal tumors B © Jun Wang, MD, PhD 1. D. Tubular adenoma has tubular glands lined by columnar cells with elongated hyperchromic nuclei. Hyperplastic polyp has star-shaped lumen and no adenomatous changes (elongated hyperchromic nuclei) or significant atypia. Intramucosal adenocarcinoma is an adenocarcinoma limited to mucosa only, and has irregular glands lined by atypical cells. Sessile serrated adenoma has features of both hyperplastic polyp and adenomatous polyp . Villous adenoma is an adenomatous polyp with more than 75% of villous components. 2. A. Numerous polyps with adenomatous changes, and family history of early onset colon cancers is highly compatible with familial adenomatous polyposis . Gardner syndrome is a type of familial adenomatous polyposis , with additional manifestations including fibromatosis, osteomas, epidermal cysts, etc. Juvenile polyposis is characterized by multiple organ involvement of juvenile polyp , that h

Practice question answers  Intestinal tumors A © Jun Wang, MD, PhD 1. A. This patient has iron deficiency anemia. In older population, iron deficiency anemia  is  often caused by chronic gastrointestinal bleeding and requires further investigation . Genetic counseling is recommended when a family history is suggestive of a genetic disorder, as seen in this patient, who might harbor BRCA mutations, a condition associated with ovarian epithelial neoplasms and breast cancers . However, this patient has no identifiable symptoms or sign of breast or ovarian neoplasm, as suggested by negative physical examination or image studies. Hemoglobin electrophoresis is used to detect hemoglobin abnormality, usually presents with anemia at childhood. Lymphocytes phenotyping may be used for primary immunodeficiency or lymphocytic neoplasms . Abnormal platelet function usually presents with petechiae. 2. B. This polyp has star-shaped lumen and no adenomatous changes (elongated hyperchro