Chapter 17 (Part 3): Anus and Peritoneum

Question 1

What cancer is more likely to arise above and below the Pectinate Line?

Answer 1

Above: Adenocarcinoma

Below: Squamous Cell Carcinoma

Question 2

What cancer is most likely to arise in the Upper, Middle, and Lower thirds of the Anal Canal?

Answer 2

Upper: glandular carcinoma
Middle: Cloacogenic Carcinoma
- basaloid tumors with immature cells from basal layer
Lower: Squamous Cell Carcinoma
- often HPV associated (Condyloma Acuminatum)

Question 3

What are Hemorrhoids?

What is the difference between External and Internal Hemorrhoids?

Answer 3

• variceal dilations of anal/perianal submucosal venous plexuses (straining, pregnancy, cirrhosis)

External: below anorectal line (PAINFUL)
- indicate HEPATIC pathology

Internal: above anorectal line (PAINLESS)
- usually caused by STRAINING

Question 4

What is Acute Appendicitis?

Who does it commonly affect and what complication can it lead to?

Answer 4

• inc. in intraluminal pressure that blocks venous outflow, usually by stool or worms in children and elderly (RLQ pain at McBurneys point)
• neutrophils enter muscularis propria and can cause suppurative necrosis & acute gangrenous appendicitis

PERFORATION = HIGHEST MORBIDITY

Question 5

Carcinoid Tumor of Appendix vs Mucocele

What can Mucocele lead to? (PP)

Answer 5

CT: most common appendix tumor

• well-differentiated neuroendocrine tumor
• solid, benign swelling at distal tip of appendix

M: dilate appendix full of mucous

• either obstructed or from mucinous cystadenoma
• adenocarcinoma = intraperitoneal seeding

Pseudomyxoma peritonei –> invades through appendiceal wall and cause mucus ascites and intraperitoneal seeding

Question 6

What causes these:

1. Sterile Peritonitis
2. Acute Hemorrhagic Pancreatitis
3. Foreign Material Peritonitis
4. Endometriosis
5. Ruptured Dermoid Cyst

Answer 6

all are forms of peritonitis or can cause peritonitis

1. bile or pancreatic enzyme leakage
   
   • can see bacterial superinfection
2. pancreatic enzymes and fat necrosis (bacterial spread)
3. due to objects introduced surgically
   
   • foreign body granuloma formation/fibrous scars
4. hemorrhage into peritoneal cavity
5. keratin release causing granulomatous rxn
   
   • cyst full of hair, skin, sebacceous material

Question 7

What are two causes of Peritoneal Infection?

What are 5 common causes of Peritoneal Infection? (E/S/S/E/C)

Answer 7

1. GI structure perforation –> bacteria into cavity
2. spontaneous peritonitis with obvious source
   • common in pts with cirrhosis and ascites

Causes: E. coli, Streptococci, S. Aureus, Enterococci, C. Perfringens

membranes become dull gray with exudation and suppuration (localized abscess formation)

Question 8

What is Sclerosing Retroperitonitis?

Answer 8

• aka Idiopathic Retroperitoneal Fibrosis (ORMONG)
• dense fibrosis that can compress ureters and abdominal aorta, causing back/abdominal pain and Acute Renal Failure (inc. ESR/CRP)
• subset associated with IgG4 disease

Question 9

What are two Primary Peritoneal Tumors? (M/DRC)

Answer 9

1. Mesothelioma (asbestos exposure)
2. Desmoplastic Round Cell Tumor (kids)
   • aggressive, looks like Ewing Sarcoma
   • has t(11;22)(p13;q12) = EWS-WT1 fusion gene

secondary metastases are MUCH more common and are virtually all malignant with poor prognosis