GI

Question 1

For collagenous colitis and lymphocytic colitis, describe:
Clinical associations (gender, dz)
Primary histologic ftrs

Answer 1

collagenous (F»M)
lymphocytic (M=F)
Both associated with celiac (lymphocytic more so), and NSAID use

collagenous also assoc. with DM, thyroid problems, and rheumatoid arthritis

Histology:
Both have 1) increase LP cellularity with lymphocytes, p.c.s and eosinophils 2) surface infiltration by lymphocytes and 3) degenerative surface epithelial changes (pyknosis, loss of mucin, etc.)

(Note lymphs in epithel. over an aggregate are NORMAL)

Collagenous has 1) more eos and scattered polys (not present in lymphocytic) 2) collagen table with trapped capillaries and surface epithelium often stripping from collagen (also some epithelial eosinophils- not so in lymphocytic)

Question 2

For Juvenile Polyposis:

• Genetics and inheritance (and associated disorder)
• The criteria for classification
• Associated clinical features, and cancer risk
• Histology and differentiating features from mimics

Answer 2

Genetics - SMAD4 gene mutation is the most common identifed, but most are unknown
Inherited in AD fashion in most cases, but many have de novo mutations

Also associated with Hereditary hemorrhagic telangiectasia (also has SMAD4 mutations)

Criteria - 
1 of 3:
1) >3 Juv polyps (can range from 3 to 10 per diff. algorithms)
2) 1 or more JP outside of colon
3) Any JP with a FHx of JP

(Note, the VAST majority of JPs are sporadic)

Many patients have hydrocephalus, mental problems, Meckels and malrotation
Increased risk of Primarily CRC, also some Pancreatic and gastric

Histo - cystically dilated glands (can have mucin or crypt abcesses, stroma expanded by inflammation, edema, and some smooth muscle (if it becomes prominent, it can mimic Peutz Jeugers)
Often lobular and ulcerated with granulation tissue

Question 3

For Pyloric Gland adenoma:
Age, site, associated disorders
histology
risk of dysplasia / carcinoma
IHC profile relative to other polyps

Finally treatment recommendations)

Answer 3

Usually much older patients (median 75 yrs), usually in body / fundus (these are usually in F&raquo_space;M), but some occur in gallbladder, duodenum, and main pancreatic duct

1/3 are Associated with AMAG

closely packed pyloric type glands (cuboidal to low columnar cells with eosinophilic or ground glass cytoplasm. Nuclei are round W/O prominent nucleoli

LGD seen in 12%
HGD seen in 39%
Carcinoma 10-15%

+ for MUC5a (like foveolar-type) but also + for MUC6+ (neg. in foveolar type)
Also CDX2 and MUC2 neg (except where IM occurs - MUC2 (intest. mucin) and CDX2 are intestinal markers)

In report say:

1) complete excision recommended
2) biopsy of background mucosa helpful (associated with background disease)

Question 4

What is diverticular disease-associated colitis?

Answer 4

It is segmental colitis affecting usually just the sigmoid colon that can mimic perfectly UC or Crohn’s.

SO in old pts without a hx of IBD and sigmoid-limited colitis, shy away from IBD and offer this as a differential.

Question 5

How do you s.o. colon bxs for watery diarrhea that only show some surface lymphocytosis and lack other features?

Answer 5

Descriptive diagnosis and
Give DDX of early lymphocytic colitis, NSAID-associated changes, or resolving colitis

Also, if in a child, add to the DDX early auto-immune enteropathy

Question 6

For Peutz-jeghers give:
Genetics and inheritance
Criteria, clinical features and associated neoplasms

Histology of polyps (and their significance for cancer risk)

Answer 6

Mutation in LKB1 (aka STK11) (serine threonine kinase TS gene) acts through MTOR pathway
(AD inheritance, but many de Novo)

Criteria - 2 or more PJP OR 1 PJP in pt with FHx OR with mucosal hyperpigmentation
OR mucocutaneous pigmentation with FHx

Associated skeletal problems (scoliosis and club foot)
Neoplasms - Colorectal AC, small bowel and stomach CA, Pancreatic AC, Breast CA
Also SEX CORD STROMAL tumors with annular tubules and ADENOMA MALIGNUM of the cervix

Histology - Lobular architecture and lots of smooth muscle bands dissecting between dilated crypts (NOTE - the epithelium is NOT neoplastic, and cancer or dysplasia is almost never found in the polyps themselves)
Also, the histology is best seen in the small bowel - stomach and colon polyps can have overlapping features with other hamartomatous polyps

Question 7

Explain difference between Complete vs Incomplete IM and the significance of them

Answer 7

Incomplete - Goblet cells with intervening gastric type foveolar cells (This is the kind that is more common in barret espophagus, and is believed to be more likely to progress to dysplasia)

Complete - Goblet cells with intervening intestinal type cells (No cytoplasmic mucin - this is more likely to be seen in gastric IM, and possibly less likely to progress to dysplasia)

Question 8

What is the relative risk of malignant transformation in gastric adenomas?

Answer 8

Flat dysplasia > gastric adenoma with intestinal diff (paneth cells and/or goblet cells - not both needed) - usually associated with background IM > ademonas with gastric (foveolar) differentiation (not as much assoc with background IM and rare in US)