140. Pathology Small Intestine Flashcards
What is the difference in function b/w Villi and Crypts components.
How do the duodenum, jejunum, and ileum look differently on histo?
Villi: 8:1 ratio of absorptive cells to goblet cells
Crypts: undifferentiated stem cells, Paneth cells, neuroendocrine cells, goblet cells (regeneration, secrete water, present IgA, antimicrobial peptides)
Duodenum: Brunner glands (tubuloalveolar glands forming lobules of variable sizes + located in submucosa)
Jejunum: nothing
Ileum: Peyer Patches (large aggregates of lymphoid tissue in mucosa/submucosa, germinal centers - no goblet cells, loss of villous architecture - normally flatten out mucosa)
Puetz Jeghers Polyp
- epidemiology
- genetics
- sx
- histo
- complications
AD/de novo, 1/200k ppl
epi: 20s-30s, polyps thru GI tract (most jejunum), sporadic polyps rare
Genes: mutation in STK11/LKB1 gene
Sx: intestinal polyposis, mucocutaneous melanin pigmentation, abd pain, intussusception, bleeding
Histo: branching bundles of smooth muscle spreading throughout polyp (arborization); disorganized/hyperplastic mucosal glands with absorptive mucous and Paneth cells
Complications: CANCER (Breast, colon, pancreatic) - 90% cumulative lifetime risk = warrants SCREENING
Whipple’s Disease
- pathogenesis
- sx
- endo
- histo
- tx
Pgen: Tropheryma Whippleii (GNR), fecal-oral transmission (enter thru small bowel), spread via lymph/blood (heart valves, lungs, CNS)
sx: malaise, weight loss, malabsorption, diarrhea, Arthritis, Pleuritis
Endo: intestine dilated, thickened, rigid, white plaque lesions
Histo: mucosal atrophy (edematous, dilated paler areas), LP has foamy macrophages with bacteria - seen on PAS-D stain, IHC stain (Acid Fast shows MAI bacteria)
Tx: ABx - excellent response
Celiac Disease
- epidemiology
- dx
- pathogenesis
- sx
Epi: incidence in childhood (<3yo) and adults (20-40), higher in EU/US/England (1%)
Dx: 1. gluten-dependent clinical manifestations 2. celiac-disease specific antibodies 3. genetic predisposition 4. histologic features of enteropathy
PGen: Disease due to gluten and breakdown products (gliadins/glutenins) - cell-mediated (direct damage to mucosa from mucosal T cells), antibody-mediated (secreted by plasma cells leading to rxn against mucosal cells)
Celiac Disease
- serology
- genetics
- gross
- histo
- tx
Serology: needs to be eating gluten for accuracy
- Tissue Tranglutaminase Ab, Antiendomysial Ab, Deamidated Antigliaden Ab (watch for IgA deficiency!!)
Genes: assoc w/ MCHII - 95% carry HLA DQ2/9 (some normal ppl have this)
Gross: mucosa flattens, loses ridges
Histo: 1. Villous blunting, 2. Increased intraepithelial lymphocytes, 3. Increased LP inflammation, 4. Crypt elongation
TX: gluten free diet
Complications: refractory sprue (no improvement GF diet), Ulcerative Jejuno-ileitis, Enteropathy assoc T Cell Lymphoma (diffuse infiltration displaces epithelium)
Crohn’s Disease
- epidemioogy
- etiology
- dx
- sx
Epi: US, N EU, Scandinavian countries
Etiology: unknown, combo of environment (high SES, NSAID use, high refined sugar diet, low fiber diet), abnormalities in immune regulation, genetic predisposition
Dx: clinical findings with radio/endo/path findings
Sx: vary by location/severity - diarrhea +/- blood, weight loss, fever, extraintestinal (arthropathies, peripheral arthralgias, granulomatous vasculitis, oral apthous ulcer)
Crohn’s Disease
- Gross
- Histo
- Complications
Gross: features of CHRONICITY and ACITIVITY
- segmental distributions (skip lesions)
- transmural inflammation
- non-caseating granuloma
- strictures, ulcers, fistula
- creeping fat on serosa (2/2 transmural inflammation)
- cobblestoning of mucosa 2/2 mucosal damage
Histo: ulcerations, surrounding acute inflammation, granulomas (collections of histiocytes)
Complications: strictures = intestinal obstructions; perforation/fistula formation, toxic megacolon, dysplasia = adenocarcinoma (need increased surveillance)
Acute Appendicitis
- Pathogenesis
- Sx
- Gross
- Histo
- Complications
PGen: mucosal insult due to fecalith, lymphoid hyperplasia, tumor followed by bacterial infection spreading outward form mucosa into/thru wall of organ
Sx: periumbilical to RLQ pain, anorexia, nausea, fever, leukocytosis (peritonitis if perforated)
Gross: swelling/hyperemia of appendix (congested blood vessels), serosa covered with fibrin/pus, dilated lumen
Histo: mucosal ulceration, suppurative acute inflammation of ALL layers of appendix (mixed inflammatory infiltrate)
Complications: perforation, periappendical abscess, diffuse peritonitis, fistula formation (appendix to intestine/bladder)
Neuroendocrine Neoplasms
- distribution
- gross feature
- histo
- prognostic factors
Disto: most in midgut, then hindgut, then foregut
Gross: constricts lumen
Histo: cells with SALT + PEPPER Chromatin, SPECKLED, nested pattern of tumor cells
Prognostics: all NETs potentially malignant - 1. size, 2. location (ileum worst), 3. depth of infiltration/lymphatic perforation
NET Syndromes
- Carcinoid Syndrome
- Gastrinoma Syndrome
- Somatostatinoma Syndrome
- Cushing’s Syndrome
CS: flushing, asthma-like attacks, diarrhea, right side HF due to EXCESS 5HT
GS: ZES (high gastrin)
SS: rare mild DM due to less insulin release, steatorrhea/gallstones (less CCK), achlorhydria (less gastrin) EXCESS STT
CuS: rare overproduction of ACTH
