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Questions and Answers
Which type of small intestinal malignancy is most commonly associated with obstructive jaundice?
What is a common predisposing factor for developing adenocarcinoma in the small intestine?
Which of the following statements about neuroendocrine tumors is true?
What is the survival rate at five years for Enteropathy-associated T cell Lymphoma?
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What mutation is frequently associated with traditional serrated adenoma?
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What are the main mutations involved in the neoplastic progression of conventional adenomas?
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Which type of lymphoma is more common in the West?
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Which condition may result in a change in bowel habit or intussusception due to large adenomatous polyps?
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Which dietary factor is associated with a decreased risk of conventional adenoma?
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What is the most common location for conventional adenomas?
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What is a characteristic feature of juvenile polyps?
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Which type of polyp shows glandular disorganization and is associated with a hamartomatous appearance?
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What is a common presentation of advanced adenocarcinoma of the large bowel?
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Which environmental factor is notably linked to the development of adenocarcinoma of the large bowel?
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What percentage of adults at autopsy show the incidence of adenomatous polyps?
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Which condition is associated with a 50% risk in the genetic lineage of first-degree relatives?
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Which of the following presentations is associated with cecal carcinomas?
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What percentage of cases are noted to be multicentric among adenocarcinomas?
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Study Notes
Small Intestinal Neoplasms
- Small intestinal malignancy is uncommon.
- Obstructive jaundice may occur and can progress to carcinoma.
Adenocarcinoma
- Most commonly found in the duodenum, particularly in the periampullary region.
- Celiac disease is a predisposing factor.
- Occasionally associated with neurofibromatosis type I.
Neuroendocrine Tumors
- Can occur in the appendix and small intestine, sometimes in multiple locations.
- Well-differentiated, malignant neuroendocrine tumors of the small intestine often have extensive local spread.
- Metastasis is infrequent, but can occur in the regional lymph nodes, liver, bone, skin, and thyroid.
- May produce vasoactive peptides like substance P, serotonin, and gastrin.
- Can cause carcinoid syndrome if they metastasize to the liver and impair its function, leading to an inability to metabolize vasoactive peptides.
Non-Hodgkin Lymphoma
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B-cell:
- MALT lymphoma is more common in the West.
- Immunoproliferative small intestinal disease (IPSID), also known as alpha chain disease or Mediterranean lymphoma.
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T-cell:
- Enteropathy-associated T-cell Lymphoma is usually associated with celiac disease after 10-20 years of malabsorption.
- Poor prognosis with a 5-year survival rate of 11%.
Adenomatous Polyps
- Frequency increases with age.
- Less common in Black individuals than White individuals.
- Familial predisposition is observed.
- Most adenomatous polyps are asymptomatic.
- Bleeding may occur due to twisting or vascular obstruction.
- Large polyps can cause changes in bowel habits and intussusception.
Pathogenesis of Adenomatous Polyps
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Conventional Adenoma:
- Neoplastic progression follows an adenoma-carcinoma sequence involving APC, beta-catenin, KRAS, and TP53 mutations.
- Approximately 5% of conventional adenomas also have high levels of microsatellite instability (MSI-H).
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Traditional Serrated Adenoma:
- Associated with BRAF or KRAS mutations and progress with beta-catenin mutation or CpG island methylation.
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Sessile Serrated Adenoma:
- Associated with BRAF mutation and progress with high levels of microsatellite instability through MLH1 hypermethylation.
Etiology of Adenomatous Polyps
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Conventional Adenoma:
- Associated with smoking, high BMI, and a diet rich in red meat.
- Decreased risk is associated with dietary fiber intake, fruit consumption, and folate intake.
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Sessile Serrated Adenoma:
- Associated with a high-fat and meat diet, smoking, alcohol, and high BMI.
Location of Adenomatous Polyps
- Conventional Adenomas: More common in the left hemicolon.
- Sessile Serrated Adenoma: More common in the proximal colon.
- Traditional Serrated Adenoma: More common in the rectosigmoid colon.
- Approximately 30-35% of adults have adenomatous polyps at autopsy.
- Most are 5 mm in diameter.
Mixed Hyperplastic-Adenomatous Polyps
- May have malignant potential due to the presence of adenoma-like areas with abnormal proliferation.
Juvenile Polyp
- Most frequent colonic polyp in children, also found in 33% of adult cases.
- Often presents with rectal bleeding and can undergo autoamputation, with polyp passed per rectum.
Multiple Juvenile Polyposis
- Rare and potentially life-threatening.
- Associated with adenomatous polyps and adenocarcinoma of the large bowel, duodenum, stomach, pancreas.
Pathology of Juvenile Polyp
- Often shows ulceration covered by granulation tissue at the surface.
- Cystically dilated glands beneath the surface are filled with mucus, lacking atypical features and separated by inflamed and edematous stroma.
Peutz-Jeghers Polyps
- Lack of atypia.
- Disorganization of glands with several cell types, including Paneth cells.
- Smooth muscle fibers from the muscularis mucosae contribute to a hamartomatous appearance.
- The pattern of glandular disorganization and epithelial misplacement can simulate invasion, but should not be confused with malignancy.
- Can be associated with adenomatous polyps with marked atypia and colorectal adenocarcinoma.
Adenocarcinoma of the Large Bowel
- Equal incidence in males and females.
- Mean age of diagnosis is 62 years.
Presentation of Large Bowel Adenocarcinoma
- Often indicates advanced disease.
- Symptoms can include rectal bleeding, change in bowel habits, anemia from chronic blood loss, vague abdominal pain, and intestinal obstruction (common with tumors in the left colon, rare with tumors in the cecum or ascending colon).
- 25% of cecal carcinomas may present with signs suggestive of appendicitis.
- Perforation, while rare, can occur at the site of the carcinoma or in the cecum due to distention caused by an obstructing rectosigmoid carcinoma.
Location of Large Bowel Adenocarcinoma
- 50% occur in the rectosigmoid area, with a relative decrease in incidence as the tumor location shifts towards the proximal colon.
Correlations Between Clinical Features and Anatomic Subsite
- Right-sided tumors are more common in elderly individuals, Black individuals, and those with diverticular disease.
- Multicentricity occurs in 3-6% of cases.
Pathogenesis of Large Bowel Adenocarcinoma
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Environmental Factors:
- Dietary factors, particularly fat and animal protein, can influence intestinal microflora and the chemical composition of intraluminal content.
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Genetic Factors:
- Predisposition is observed in familial polyposis (nearly 100% by age 50 years) and hereditary nonpolyposis colorectal cancer syndrome (Lynch syndrome) with a 50% risk to first-degree relatives due to mutated genes responsible for DNA mismatch repair.
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Lynch Syndrome:
- Resulting from inherited mutations in genes affecting DNA mismatch repair, which corrects errors in DNA replication.
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Description
Explore the various types of small intestinal neoplasms, including adenocarcinoma and neuroendocrine tumors. Understand their characteristics, risk factors, and potential complications such as obstructive jaundice and carcinoid syndrome. This quiz also covers associated conditions like celiac disease and neurofibromatosis.
