Gastrointestinal - Pathology (1) Flashcards

Question

Diverticulosis * Definition * Caused by... * Symptoms * Complications

Answer 1

* Definition * Many false diverticula of the colon, commonly sigmoid. * Common (in ~50% of people \> 60 years). * Associated with low-fiber diets. * Caused by... * Increased intraluminal pressure and focal weakness in colonic wall. * Symptoms * Often asymptomatic or associated with vague discomfort. * A common cause of hematochezia. * Complications * Diverticulitis, fistulas.

Answer 2

* Definition * Inflammation of diverticula classically causing LLQ pain, fever, leukocytosis [B]. * Sometimes called “left-sided appendicitis” due to overlapping clinical presentation. * Symptoms * May perforate --\> peritonitis, abscess formation, or bowel stenosis. * Stool occult blood is common +/– hematochezia. * May also cause colovesical fistula (fistula with bladder) --\> pneumaturia. * Treatment * Give antibiotics.

Answer 3

* Definition * Pharyngoesophageal **false** diverticulum [A]. * Herniation of mucosal tissue at Killian triangle between the thyropharyngeal and cricopharyngeal parts of the inferior pharyngeal constrictor. * Most common in elderly males. * Presenting symptoms * Dysphagia, obstruction, foul breath from trapped food particles (halitosis).

Answer 4

* Definition * **True** diverticulum. * Persistence of the vitelline duct. * May contain ectopic acid–secreting gastric mucosa and/or pancreatic tissue. * Most common congenital anomaly of the GI tract. * Symptoms * Can cause melena, RLQ pain, intussusception, volvulus, or obstruction near the terminal ileum. * Contrast with omphalomesenteric cyst = cystic dilation of vitelline duct. * Diagnosis * Pertechnetate study for uptake by ectopic gastric mucosa. * **The five _2_’s:** * **_2_** inches long. * **_2_** feet from the ileocecal valve. * **_2_**% of population. * Commonly presents in first **_2_** years of life. * May have **_2_** types of epithelia (gastric / pancreatic).

Answer 5

* Definition * “Telescoping” of 1 bowel segment into distal segment, commonly at ileocecal junction. * Compromised blood supply --\> intermittent abdominal pain often with “currant jelly” stools. * Age * Unusual in adults (associated with intraluminal mass or tumor that acts as lead point that is pulled into the lumen). * Majority of cases occur in children (usually idiopathic; may be associated with recent enteric or respiratory viral infection). * Abdominal emergency in early childhood.

Answer 6

* Definition * Twisting of portion of bowel around its mesentery * Can lead to obstruction and infarction. * Can occur throughout the GI tract. * Midgut volvulus more common in infants and children. * Sigmoid volvulus more common in elderly.

Answer 7

* Definition * Congenital megacolon characterized by lack of ganglion cells/enteric nervous plexuses (Auerbach and Meissner plexuses) in segment on intestinal biopsy. * **Think of Hirsch**_sprung_** as a giant spring that has _sprung_ in the colon.** * Cause * Due to failure of neural crest cell migration. * Associated with mutations in the RET gene. * Risk increases with Down syndrome. * Presentation * Bilious emesis, abdominal distention, and failure to pass meconium in the first 48 hours of life, ultimately manifesting as chronic constipation. * Dilated portion of the colon proximal to the aganglionic segment, resulting in a “transition zone.” * Involves rectum. * Diagnosis * Diagnosed by rectal suction biopsy. * Treatment * Resection.

Answer 8

* Adhesion * Fibrous band of scar tissue * Commonly forms after surgery * Most common cause of small bowel obstruction. * Can have well-demarcated necrotic zones. * Angiodysplasia * Tortuous dilation of vessels --\> hematochezia. * Most often found in cecum, terminal ileum, and ascending colon. * More common in older patients. * Confirmed by angiography. * Duodenal atresia * Causes early bilious vomiting with proximal stomach distention (“double bubble” on X-ray) because of failure of small bowel recanalization. * Associated with Down syndrome.

Answer 9

* Ileus * Intestinal hypomotility without obstruction --\> constipation and decreased flatus * Distended/tympanic abdomen with decreased bowel sounds. * Associated with abdominal surgeries, opiates, hypokalemia, and sepsis. * Ischemic colitis * Reduction in intestinal blood flow causes ischemia. * Pain after eating --\> weight loss. * Commonly occurs at splenic flexure and distal colon. * Typically affects elderly. * Meconium ileus * In cystic fibrosis, meconium plug obstructs intestine, preventing stool passage at birth. * Necrotizing enterocolitis * Necrosis of intestinal mucosa and possible perforation. * Colon is usually involved, but can involve entire GI tract. * In neonates, more common in preemies (decreased immunity).

Answer 10

* Definition * Masses protruding into gut lumen --\> sawtooth appearance. * 90% are non-neoplastic. * Often rectosigmoid. * Can be tubular [A] or villous [B]. * Adenomatous * Malignancy * Adenomatous polyps are precancerous. * Malignant risk is associated with increased size, villous histology, increased epithelial dysplasia. * Precursor to colorectal cancer (CRC). * The more villous the polyp, the more likely it is to be malignant * **_Villous_ = **_vill_**ain**_ous_**.** * Polyp symptoms * Often asymptomatic, lower GI bleed, partial obstruction, secretory diarrhea (villous adenomas).

Answer 11

* Hyperplastic * Most common non-neoplastic polyp in colon (\> 50% found in rectosigmoid colon). * Juvenile * Definition * Mostly sporadic lesions in children \< 5 years old. * 80% in rectum. * If single, no malignant potential. * Juvenile polyposis syndrome * Multiple juvenile polyps in GI tract * Increased risk of adenocarcinoma. * Hamartomatous * Peutz-Jeghers syndrome * Autosomal dominant syndrome featuring multiple nonmalignant hamartomas throughout GI tract, along with hyperpigmented mouth, lips, hands, genitalia. * Associations * Associated with increased risk of CRC and other visceral malignancies.

Answer 12

* Epidemiology * Most patients are \> 50 years old. * ~ 25% have a family history. * Risk factors * IBD, tobacco use, large villous adenomas, juvenile polyposis syndrome, Peutz-Jeghers syndrome. * Presentation * Rectosigmoid \> ascending \> descending. * Ascending—exophytic mass, iron deficiency anemia, weight loss. * Descending—infiltrating mass, partial obstruction, colicky pain, hematochezia. * Rarely presents as Streptococcus bovis bacteremia. * Right side bleeds; left side obstructs. * Diagnosis * Iron deficiency anemia in males (especially \> 50 years old) and postmenopausal females raises suspicion. * Screen patients \> 50 years old with colonoscopy or stool occult blood test. * “Apple core” lesion seen on barium enema x-ray [A]. * CEA tumor marker: good for monitoring recurrence, not useful for screening.

Answer 13

* **Familial adenomatous polyposis (FAP)** * Autosomal dominant mutation of APC gene on chromosome 5q. * 2-hit hypothesis. * 100% progress to CRC unless colon is resected. * Thousands of polyps arise starting at a young age * Pancolonic * Always involves rectum. * **Gardner syndrome** * FAP + osseous and soft tissue tumors, congenital hypertrophy of retinal pigment epithelium. * **Turcot syndrome** * FAP + malignant CNS tumor. * ****_Tur_**cot = **_Tur_**ban.** * **Hereditary nonpolyposis colorectal cancer (HNPCC/Lynch syndrome)** * Autosomal dominant mutation of DNA mismatch repair genes. * ~ 80% progress to CRC. * Proximal colon is always involved.

Answer 14

* There are 2 molecular pathways that lead to CRC: * Microsatellite instability pathway (~15%): * DNA mismatch repair gene mutations --\> sporadic and HNPCC syndrome. * Mutations accumulate, but no defined morphologic correlates. * APC/β-catenin (chromosomal instability) pathway (∼85%) * --\> sporadic cancer. * Order of gene events—**_AK-53_**. * Normal colon * --\> Loss of **_A_**PC gene * Decreased intercellular adhesion and increased proliferation * Colon at risk * --\> **_K_**-RAS mutation * Unregulated intracellular signal transduction * Adenoma * --\> Loss of tumor suppressor gene(s) (p**_53_**, DCC) * Increased tumorigenesis * Carcinoma

Gastrointestinal - Pathology (1) Flashcards

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