Small Intestine and Colon Pathology 3 Flashcards
Describe the features of FAP.
Autosomal dominent mutation in APC tumor suppressor gene
once second APC mutation is required, you get development of hundreds of adenomas - usually starting in late adolescence and early adulthoos
100% risk CRC adenocarcinoma - prophylactic colectomy undertaken
are at risk for adenocarcinoma trhoughout the rest of the GI tract
Describe the features of Lynch syndrome (HNPCC)
Mutation in enzymatic mismatch repair proteins - MLH1, MSH2, MSH6, PMS2
end up with microsatellite instability with increasing number of DNA mutations - including in genes that regulate cell growth
adenomas that occur in the colon hav ea greatly increased risk of malignant transformation - lifetime risk for CRC is 80%
get extra=colonic tumors too
Describe the features of Gardner’s syndrome.
In addition to FAP with the APC mutation, patients develop desmoid tumors, osteomas, epidermal cysts, dental abnormalities and thyroid tumors
Describe the features of Turcot Syndrome.
defined as a coexistence of a hereditary colon cancer syndrome along with CNS tumors
some have FAP with medulloblastoma
others have HNPCC with glioblastoma multiforme
Describe in detail the pathogenesis of colorectal cancer.
start with an adenomatous polymp
this progresses through the adenoma-carcinoma sequence with two main genetic pathways - APC/beta catenin and microsatellite instaiblity
additional mutations arise as cancer progresses
Describe the morphology of colorectal cancer.
Can occur anywhere in the colon.
vary by morphology: can be a large fungating exophytic mass or a deeply penetrating, ulcerated tumor, or an obstructive annular lesions
those associated with MIN are usually on the right side
Describe the clinical presentaiton of colon cancer.
Usually presents in the elderly with peak ages at 60-70
often insidious onset - can present with cramping, LLQ pain, changes in bowel habits and occult bleeding
some with fatigue and weakness from iron deficiency anemia
Describe screening and prevention strategies for colorectal cancer.
colonoscopy every 10 years is gold standard
if polyps are found on screening, rescreening interval may be shortened to 3-5 years
other options are stool DNA tests to check fo rmethylation markers on promoter genes, KRAS mutations and beta-actin (a reference gene for DNA quantity)
Also Fecal immunochemical test for hemoglobin
Describe the rationale for mismatch repair protein testing in CRC.
Using the revised bethesda criteria in selecting which patients to screen may miss up to 25% of patients with HNPCC, so it makes sense to just test every CRC patient for it
Describe the rationale for KRAS testine in colon cancer.
EGFR monoclonal antibodies can be used to blocked growth factor binding to inhibit downstream signaling
mutations in KRAS lead to activation of the signalling pathway regalrdess of whether EGFR is binding or not - so the monoconal antibodies wouldn’t work
Describe the most common location for small bowel adenocarcinoma.
50% occur in the duodenum - espeically at the ampulla of vater
What are the risk factors for small bowel adenocarcinoma?
FAP, Crohn’s disease and celiac disease
Describe presentaions of GI tract neuroendocrine tumors arising in the small bowel.
small bowel is the most common location! Especially the ileum
can be functional with zollinger-ellison syndrome
otherwise if they’re non-functional, presentation is usually fague with crampy abdominal pian, nausea, vomiting and weight loss
those in the ileum and jejunum are often over 2 cm in size and already show transmural invasion with metastases at the time of diagnosis. Thus, many patients present with caricnoid syndrome
Describe the presentation of a GI tract neuroendocrine tumor arising in the colon.
rare - often present as bulky, right sided high grade neuroendocrine carcinomas with similar morphology to that of small cell carcinoma of the lung
Describe the presentation of a GI tract neuroendocrine tumor arising in the rectum
more common than colonic
typically present as polyps usually less than 1 cm. favorable prognosis
Describe melanosis coli
when the colon mucosa exhibits a brown mucosa due to deposition of lipofuscin-like pigemtns in mucosal macrophages
can be associated with use of anthraceneline laxatives
Describe lymphomatosis polyposis
It’s mantle cell lymphoma of the bowel
Describe the pathogenesis of acute appendicitis
acute inflammation of at least the muscularis propria of the appendix
advanced cases with suppurative inflammation and gangrenous necrosis
Describe the morphologic findings of acute appendicitis
outer aspects growwly with thick purulent coating and marked hyperemia of the serosa
increased diameter of the appendix
you get massive inflammation with neutrophilia
Describe the clinical presentation of acute appendiciis
periumbilical pain that ultimately localizes to the right lower quadrant, with adbdominal tenderness on examination over McBurney’s Point
Nausea and vomiting follow the development of the abdominal pain
often with elevated WBC with neutrophlia
What are some helpful diagnostic tests for acute appendicitis
imagine with US or CT
What are the potential complications of acute appendicitis
perforation with periappendiceal abscess, pyelophlebitis, portal venous thrombosis, liver abscess, bacteremia, sepsis and death
Describe the typical morphology of appendiceal carcinoma
they are mucinous - typically called appendiceal mucinous tumors - can range from low to high grade
Describe the typical morphology of pseudomyxoma peritonei
it’s a gross descriptive term for the presence of abdunant mucinous material on the peritoneal surface