162. Pathology Colon Disorders

Question 1

How are tumors staged in colon?

What cells make up the colon mucosa and how do they look on histo?

What cells are in the submucosa?

What cells are in the muscularis propria?

Answer 1

Tis (in situ) - only mucosa
T1 - invades submucosa
T2 - invades muscularis propria
T3 - invades serosa

Epithelium: absorptive cells, goblet cells (nucleus on bottom, mucin at apex), Paneth cells (R colon only - nucleus on bottom, granules near apex), Endocrine cells (fine granules at base, nucleus on top)
LP: plasma cells, eosinophils (red rounds), lymphocytes
MM

Submucosa: loose ct, ganglion cells (Meissner’s Plexus)

MP: ICM, OLM, Ganglion cells (Auerbach’s plexus)

Question 2

Colitis types

• etiologies
• infectious colitis: histo
• pseudomembranous: define, causes, histo, gross
• microscopic colitis: define, histo

Answer 2

Colon inflammation: infectious, immune (IBD), vascular (ischemia), meds

Infectious colitis: ACTIVE (acute) inflammation - CRYPTITIS (neutrophils in epithelium), CRYPT ABSCESSES (neutrophils in crypt lumina)

Pseudomembranous Colitis: pseudomembrane (necrotic epithelial cells, acute inflammatory cells, fibrinous material), crypts distended by mucin/neutrophils, loss of epithelial lining
caused by C Dif Colitis (most common, test for toxin in stool), ischemia, IBD
Gross: discrete, raised creamy yellow plaques of 1-5mm

Microscopic Colitis: chronic non-bloody diarrhea
Types: lymphocytic colitis (more lymphs in LP and epithelium)
Collagenous colitis (subepithelial collagen deposition)

Question 3

UC

• define, location, clinical features
• histo
• complications

CD

• define, location, clinical features
• histo

Answer 3

UC

• inflammatory condition of mucosa
• begins in rectum, progresses upward to colon (CONTINUOUS)
• sx: sudden bloody diarrhea, abd pain, acute toxic megacolon (pancolitis - dilation - no peristalsis - deterioration)
• histo: chronic inflammation (lymphs/plasma cells in LP, distorted crypt architecture), active inflammation (cryptitis, crypt abscess), limited to mucosa
• gross: diffuse granular ulcerations
• comp: Toxic Megacolon (abd distention, fever, abd pain, shock), hemorrhage, CANCER, PSC!! - high risk of cholangiocarcinoma (5% UC have PSC), need screening for dysplasia

CD

• chronic discontinuous inflammation
• terminal ileum +/- colon, TRANSMURAL, SKIP LESIONS
• sx: chronic diarrhea, crampy abd pain, fever, malnutrition, fatigue, anemia, weight loss
• histo: transmural inflammation, granulomas, active inflammation, expanded submucosa
• gross: strictures, fistulas, skip lesions, cobblestoning, serpiginous ulcers

Question 4

Differentiate types of polyps: NON-neoplastic

• hyperplastic polyp
• inflammatory polyp
• solitary rectal ulcer syndrome
• hamartomatous polyp
• juvenile polyp
• puetz-jeghers syndrome

Answer 4

Hyperplastic: L Colon, Small, Mature goblet cells/absorptive cells, SERRATION (shar-shaped) in upper third of crypts only
Inflammatory: non-neoplastic mix of epithelium, stroma, and inflammation in IBD, prolapse, solitary rectal ulcer syndrome
SRUS: impaired relaxation of anorectal sphincter = recurrent abrasion/ulceration of mucosa = polyp (rectal bleeding, mucus discharge, inflammatory polyp triad)
Harmartomatous: benign, overgrowth of one normal element
- Juvenile: <5yo, in rectum (+Bleeding), surface erosion, cystic dilation, debris within dilated crypts (if multiple - can become malignant, high risk of colonic adenocarcinoma, SMAD4 mutation)
- P-J: STK11 mutation, causes mucocutaneous hyperpigmentation, high risk of malignancies (Breast, pancreas), need for surveillance, smooth muscle bundles on histo (arborization)

Question 5

Differentiate types of polyps: NEOPLASTIC

• tubular adenoma
• villous adenoma
• tubulovillous adenoma
• sessile serrated adenoma

What is the most important factor in determining malignant potential in colorectal polyps?

Answer 5

All are PRECURSOR lesions for CRC
Tubular Adenoma: high incidence with age, low grade dysplasia - darker elongated nuclei (cigar), high N:C
Villous adenoma: epithelial proliferation as slender villi, finger like projections
Tubulovillous: mix of both features
Sessile Serrated: in R colon, malignant potential, SERRATION/STAR SHAPE throughout full length of crypt base, dilation and lateral growth (ANCHOR SHAPE)

SIZE DETERMINES MALIGNANT POTENTIAL

Question 6

Colonic Adenocarcinoma

• epidemiology
• risk factors
• pathogenesis
• gross
• histo
• prognostic factors (2)

Answer 6

Epi: 3rd most common neoplasm, 15% all cancer-related deaths, avg age 60, usually in rectosigmoid
RF: smoking, diet (high fat, low fiber), obesity, FAP, HNPCC
PGEN: FAP (AD, APC mutation, needs prophylactic colectomy, 100% CRC, colon covered by adenomas), HNPCC (Lynch syndrome, AD, dna MMR mutation, R colon cancer)
Gross: ulcerating, annular, polypoid mass
Histo: destroyed MM, infiltrating submucosa, high grade dysplasia (elongated nuclei, atypical mitoses, high N:C), NECROTIC DEBRIS, pools of mucus

Prognostic Factors:

1. Depth of penetration (STAGE)
2. Lymph Node Metastases