4 Flashcards
Tumors intestine Benign Tumors …….
Presentation:
Site:
Adenomas are Benign neoplastic polyps (often pedunculated tumors).
- has the possibility to progress to colonic adenocarcinoma i.e. Precancerous
- Rare in small intestine but more common in colon.
- Presentation: - Commonly asymptomatic
- Occult rectal bleeding and iron deficiency anemia,
- Rarely, overt rectal bleeding
Adenomatous polyps are Classified into Four subtypes:
1-Tubular Adenoma:
- The most common ,Solitary (0.5-2.5 cm), small, pedunculated
- It consists of proliferating tubular glands that show variable degrees of dysplasia. - Commonest in Rectosigmoid. - The risk of cancer is uncommon
Villous Adenoma: - only 1% are villous
- It is often solitary (up to 10 cm) large and sessile
- It consists of villous projections showing dysplasia - Commonest in rectum and rectosigmoid.
- Precancerous → The risk of cancer colon is high (about 40% of cases) due to frequent severe dysplasia
3-Tubulovillous Adenoma:
4- Familial Adenomatous Polyposis: (Familial polyposis coli)
- Uncommon hereditary (autosomal dominant) disease.
- The entire colon shows hundreds of small adenomatous polyps
- Most polyps are tubular adenomas; occasional polyps have villous features. - Polyps usually become evident in adolescence or early adulthood
- It is highly precancerous: The risk of colonic cancer is 100% by midlife ( at the age of 30-40 years), unless a prophylactic colectomy is performed.
Risk factors for malignancy in adenomas:
Pathogenesis:
Inactivation of
- Polyp size : Adenoma larger than 2 cm (40% risk of malignancy)
- Multiple polyps
- Histologic architecture Polyps with increased villous component
- Severity of epithelial dysplasia
Pathogenesis:
Inactivation of adenomatous polyposis coli (APC) suppressor gene
Malignant Tumors of intestinal
1- Carcinoma (more common in colon).
2- Malignant lymphoma (more common in small intestine).
3- Carcinoid (more common in small intestine and appendix).
Carcinoma of Large Intestine
incidence and mortality :
Age:
Originate from:
incidence and mortality : Third
Age: Usually above 45 years.
May occur in younger ages (around or below 30 y) on top of familial polyposis.
Originate from Colorectal cancers most frequently originate from adenomas. Cancer that arises de novo from colonic mucosa appears to be low.
Carcinoma of Large Intestine: Predisposing factors (Risk factors): + Sites
1- Familial polyposis, villous adenoma, tubular adenoma (Adenomatous polyps)
2- Dietary Factors:
- High red meat and animal fat consumption NEW
- Low-fiber diet asouls
- Diet low in fruits and vegetables
3 - Dysplasia of ulcerative colitis
4- Genetics: multiple mutations are involved as Loss of the APC and p53 tumor
1) 60% in rectum and sigmoid (rectosigmoid)
2) 25% in cecum/ascending colon
3) 10% in transverse colon 4) 5% in descending colon
Gross , Carcinoma of Large Intestine
Microscopy
1- Polypoid mass fungating into the lumen. Commonly in Rt sided cancers
2- Malignant ulcer: irregular with raised everted edges, necrotic floor indurated base.
3- Infiltrating growth (→ annular type): → narrowing of the lumen. Commonly in Left sided cancers
Microscopy: 1- Adenocarcinoma: most common
, 2- Mucoid carcinoma: characterized by excess extracellular mucin secretion
3- Signet ring cell carcinoma
Spread , Clinical Features: Carcinoma of Large Intestine
Spread: 1- Direct spread: To urinary bladder, vagina (fistulae may form)
2- Lymphatic spread: To mesenteric and paraortic lymph nodes.
3- Blood spread: First to liver then lungs and bone,
4- Tscoelomic spread: Lead to peritoneal metastasis and hemorrhagic ascites. Krukenberg tumors may occur in females.
Clinical Features: - Asymptomatic for years
- Cecal & right colonic cancers:→ occult blood in stool, iron deficiency anemia, fatigue
- Left-sided lesions:
- occult bleeding, changes in bowel habits (Constipation or diarrhea),
- reduced caliber stools
- Intestinal obstruction or discomfort in left lower quadrant.
- Intestinal perforation producing septic peritonitis. - Fistula between intestinal loops, bladder, vagina …
Staging ,Diagnosis Carcinoma of Large Intestine
Staging: modified Dukes‘ staging system
TNM Staging of Colon Cancers
Diagnosis: - Positive occult blood in stool,
- Colonoscopy (gold standard), with biopsy, barium enema
- Elevated blood levels of carcinoembryonic antigen (CEA, follow up) usually is used to detect recurrences
Dukes’ staging
Stage A: The tumour is confined to the
submucosa or muscle layer.
Stage B: The tumour has spread through the muscle layer, but does not yet
involve the lymph nodes.
Stage C: Any tumour involving lymph nodes.
TNM Staging of Colon Cancers
Tumor (T) Tis = in situ (limited to mucosa)
T1 = invasion of submucosa T2 = invasion of muscle layer T3 = invasion through muscle layer into subserosa
T4 = invasion of adjacent organs
Lymph Nodes (N)
N0 = no lymph node metastasis
N1 = 1 to 3 positive pericolic nodes
N2 = 4 or more positive pericolic nodes
N3 = distant positive node
Distant Blood Metastases (M) M0 = no distant metastasis
M1 = any distant metastasis
Carcinoid Tumor
Arises from ……. Secrete………..
Incidence
Behavior
argentaffin (neuroendocrine) cells which are normally scattered along the mucosa of the gastrointestinal tract
- Secrete bioactive products as serotonin (so, it is Neuroendocrine tumor)
Incidence: Carcinoid Tumor
- form < 2% of colorectal malignancies
- but 50% of small intestinal malignant tumors.
Behavior: The tumor is locally malignant, or malignant.
- Metastatic potential correlates with the site of origin, the depth of local penetration, and the size of the tumor.
1- Size larger than 2 cm
2- depth of invasion (> 50% of bowel thickness)
3- the site of origin
Carcinoid tumors of stomach, rectum & appendix → Invade locally but rarely metastasize
Carcinoid tumors of small intestine (primarily terminal ileum) → Invade & metastasize
Carcinoid Tumor
Locations (Sites):
Locations (Sites):
- Vermiform appendix : - Most common site (>40% of cases) - Usually <2 cm, which is too small to metastasize to liver
- Small bowel (20-30% of cases): - Majority occur in the terminal ileum - Commonly metastasize to liver
- Less common locations include esophagus, stomach, colon collectively (10% of
Carcinoid Tumor
Gross, Microscopy
Gross:
- A polypoid, submucosal nodule, or multiple nodules.
- A characteristic feature is a firm (due to desmoplasia), yellow appearance
Microscopy:
- Groups of small monotonous cells (No variation in cell & nuclear size)
- The cells show cytoplasmic granules (stainable with silver) and round-to-oval stippled nuclei.
With characteristic Salt & pepper nuclear chromatin
By electron microscopy:- the tumor cells contain cytoplasmic, membrane-bound Secretory granules
Carcinoid Tumor: Carcinoid syndrome is manifested by:
1-Skin flushing (75%–90% of cases), & edema, (due to vasodilation)
2- Diarrhea (>70% ), cramps, nausea, vomiting (due to increased bowel motility)
3- Bronchoconstrictive attacks, wheezing and dyspnea (25% of cases)
(asthma-like attacks ).
4- Systemic fibrosis: principally in right side of heart → Serotonin increases collagen production in the valves → Fibrosis of tricuspid & pulmonary valves
→→→ Tricuspid regurgitation and pulmonary stenosis
