كلية الطب · "polyp" is a morphologic term, and no histologic diagnosis is...

Colorectal polyps

• Polyp is a clinical term that describes any projection from the surface of the intestinal mucosa regardless of its histologic nature.

• Colorectal polyps may be classified as A) Neoplastic (tubular adenoma, villous adenoma,

tubulovillous adenomas).

B) Hamartomatous (juvenile, Peutz-Jeghers, Cronkite-Canada and Cowden).

C) Inflammatory (pseudopolyps and benign lymphoid polyp)

D) Hyperplastic.

Polyps of the Colon & Rectum

Colorectal polyps are masses of tissue that project into the lumen. sessile or pedunculated,

benign or malignant,

mucosal, submucosal, or muscular lesions.

"Polyp" is a morphologic term, and no histologicdiagnosis is implied.

Polyposis is a term reserved for the presence of many polyps in the large bowel.

Estimates of the incidence of colonic and rectal polyps in the general population range from 9% to 60%.

Polyps of the Colon & Rectum

• Approximately 50% of polyps occur in the sigmoid or rectum.

• About 50% of patients with adenoma have more than one lesion, and 15% have more than two lesions.

• Approximately 25% of patients who have five or more adenomatous polyps have a synchronous colon cancer at the initial colonoscopy.

• An increased incidence of adenomas in breast cancer patients has been reported.

Polyps of the Large Intestine.

Type Histologic Diagnosis

Neoplastic •Adenoma

1. Tubular adenoma (adenomatous

polyp) 75-80%.

2. Tubulovillous adenoma

(villoglandular adenoma) 8-15%.

3. Villous adenoma (villous papilloma)

5-10%.

•Carcinoma

Hamartomas •Juvenile polyp

•Peutz-Jeghers polyp

Inflammatory Inflammatory polyp (pseudopolyp)

Benign lymphoid polyp

Hyperplastic

Miscellaneous Lipoma, leiomyoma, carcinoid

Neoplastic Polyps

Adenomatous polyps are common, occurring in up to 25% of the population older than 50 years of age.

By definition, these lesions are dysplastic. Invasive carcinoma is present in 5% of all adenomas, but the incidence

correlates with the size and type of the adenoma Tubular adenomas are associated with malignancy in only 5% of cases,

whereas villous adenomas may harbor cancer in up to 40%. Tubulovillousadenomas are at intermediate risk (22%).

Invasive carcinomas are rare in polyps smaller than 1 cm; the incidence increases with size. The risk of carcinoma in a polyp larger than 2 cm is 35 to 50%.

Although most neoplastic polyps do not evolve to cancer, most colorectal cancers originate as a polyp.

It is this fact that forms the basis for secondary prevention strategies to eliminate colorectal cancer by targeting the neoplastic polyp for removal before malignancy develops.

NEOPLASTIC COLORECTAL POLYPS

Type Histologic features Incidence (%) Invasive malignancy (%)

Adenomatous(tabular adenoma)

Branching tubules embedded in lamina propria

75 5

Villous (villous adenoma)

Finger-like projections of epithelium over lamina propria

10 40

Intermediate (tubulovillousadenoma)

Mixture of adenomatous and villous patterns

15 22

Colorectal polyps

• Hamartomatous Polyps (Juvenile Polyps):– Juvenile polyps: are not usually premalignant.

These lesions are the characteristic polyps ofchildhood but may occur at any age. The polypsare pedunculated, usually single or few in number.Commonly affecting the rectum. Bleeding is acommon symptom and intussusception and/orobstruction may occur. Because the grossappearance of these polyps is identical toadenomatous polyps, these lesions should also betreated by polypectomy.

Colorectal polyps

• Hamartomatous Polyps (Juvenile Polyps):– Peutz-Jeghers syndrome is characterized by polyposis of

the small intestine, and to a lesser extent, polyposis of thecolon and rectum. Characteristic melanin spots are oftennoted on the buccal mucosa and lips of these patients. Thepolyps of Peutz-Jeghers syndrome are generally consideredto be hamartomas and are not thought to be at significantrisk for malignant degeneration. However, carcinoma mayoccasionally develop. Because the entire length of thegastrointestinal tract may be affected, surgery is reservedfor symptoms such as obstruction or bleeding or forpatients in whom polyps develop adenomatous features.

Colorectal polyps

• FAMILIAL ADENOMATOUS POLYPOSIS ( FAP)(Familial PolyposisColi, FPC)– Aetiology:

• This rare autosomal dominant condition.• Clinically, patients develop hundreds to thousands of adenomatous polyps

shortly after puberty. The lifetime risk of colorectal cancer in FAP patients approaches 100% by age 50 years.

– Pathology:• Polyps usually start to appear at puberty, affecting the sigmoid colon and

rectum initially and by the age of 20 years the entire colon and rectum are affected by immense numbers of polyps ( at least 100), ranging from 1 mm to several cms.

• Polyps may be sessile or pedunculated.• Three histological types are recognized; the tubular, tubulo-villous, and villous.• Left untreated, carcinoma develops in 100% of the affected patients by the

fifth decade.

Colorectal polyps

• Clinical picture:– The disease usually manifests itself soon after puberty

by attacks of lower abdominal pain, diarrhoea, tenesmus with the passage of blood and mucus in the stools. Loss of weight, anaemia and general debility are common.

– Rectal examination reveals the adenomas.

• Investigations:– Barium enema shows multiple rounded filling defects

throughout the colon and the rectum.– Sigmoidoscopy or colonoscopy and biopsy prove the

nature of the disease.

Macroscopic appearance of the colon in classical familial adenomatous polyposis. The specimen shows dense carpeting of the

colonic mucosa with thousands of adenomas.

Colorectal polyps

• Treatment:– Once the diagnosis of FAP has been made and polyps

are developing, treatment is surgical.

– Three operative procedures (options) can be considered:

1. total proctocolectomy: with either an end ileostomy or continent (Kock's) ileostomy

2. Restorative proctocolectomy : with ileal pouch–anal anastomosis with or without a temporary ileostomy

3. Total abdominal colectomy with ileorectal anastomosis; the rectum is preserved, and polypi in the rectum are followed endoscopically and removed periodically.

Carcinoma of the colon

• Incidence: Colorectal carcinoma is the most common malignancy of the gastrointestinal tract. The incidence is similar in men and women.

• Risk Factors:(1) Aging: Aging is the most important risk factor for colorectal cancer, with incidence rising

steadily after the age of 50 years. More than 90% of cases diagnosed are in people older than age 50 years.

(2) Hereditary Risk Factors: Approximately 80% of colorectal cancers occur sporadically, while 20% arise in patients with a known family history of colorectal cancer.

(3) Environmental and Dietary Factors: Colorectal carcinoma occurs more commonly in populations that consume diets high in animal fat and low in fiber.

(4) Inflammatory bowel disease: Patients with long-standing ulcerative colitis are at increased risk for the development of colorectal cancer. Crohn's pancolitis have similar risk.

(5) Other Risk Factors:Cigarette smoking reportedly increases the risk of colorectal cancer . Patients with ureterosigmoidostomy are also at increased risk . Also in women, gallstones (and the consequent cholecystectomy) are associated with colorectal

cancer, especially in the right colon.

Risk Factors Associated with Colon CancerRisk Factor Comment

Geographic variation Highest risk in Western countries and lowest risk in developing countries

Age Risk increase sharply after the fifth decade

Diet Increased with total and animal fat diets

Physical inactivity Increased with obesity and sedentary life style

Adenoma Risk dependent on type and size

FAP penetrance in gene carriers 100%

HNPCC penetrance in gene carriers 80%

Hamartomatous syndromes Risk increased with Peutz-Jeghers syndrome and juvenile polyposis but not isolated juvenile polyps

Previous history of colon cancer Increased risk for recurrent cancer

Ulcerative colitis 10–20% after 20 years

Radiation Associated with a mucinous histology and poor prognosis

Ureterosigmoidostomy 100–500 times increased risk at or adjacent to the uretero-colonic anastomosis


• Pathology:– Site:

• The sigmoid colon is the commonest site (50%) probably because its contents are solid, stagnant and irritant, and it is often the seat of precancerous lesions (i.e., FAP and UC)

• Caecum and ascending colon: 25%

• Transverse colon: 20%.

• Descending colon: 5%.

• Multiple synchronous colonic cancers (i.e., two or more carcinomas occurring simultaneously) are found in 5% of patients. Metachronous cancer is a new primary lesion in a patient who has had a previous resection for cancer.


• Gross picture:– Cauliflower growth: This occurs in the right colon.– Scirrhous growth (annular and tubular): This occurs in

the left colon.– Malignant ulcer: This occurs commonly in the caecum.

• Microscopic picture– Histologically the tumour is an adenocarcinoma that

arises from the columnar epithelium. It may be well, moderately, or poorly differentiated.

– Some tumours have a colloid structure, occur in younger patients, and have a poor prognosis.


• Spread:– Direct spread:

• Carcinoma grows circumferentially and may completely encircle the bowel before it is diagnosed; this is especially true in the left colon, which has a smaller caliber than the right. It takes about 1 year for a tumor to encircle three-fourths of the circumference of the bowel.

• Longitudinal submucosal extension occurs with invasion of the intramural lymphatic network, but it rarely goes beyond 2 cm from the edge of the tumor unless there is concomitant spread to lymph nodes.

• As the lesion extends radially, it penetrates the outer layers of the bowel wall, and it may invade adjacent structures: the liver, the greater curvature of the stomach, the duodenum, the small bowel, the pancreas, the spleen, the bladder, the vagina, the kidneys and ureters, and the abdominal wall. Subacute perforation with inflammatory attachment of bowel to an adjacent viscous may be indistinguishable from actual invasion on gross examination.


• Lymphatic spread: – Cancer spreads from the colon to the following lymph

node groups, in sequence:1. Epicolic nodes on the bowel wall.2. Paracolic nodes between the marginal artery and the bowel.3. Intermediate nodes on the main vessels.4. Principal nodes alongside the superior and inferior mesenteric

vessels.

– From the principal nodes further spread occurs to the parpa-aortic lymph nodes, then to cysterna chyli and thoracic duct. The left supraclavicular lymph nodes may be involved by retrograde flow from the thoracic duct (Virchow’s glands) giving positive Troisier’s sign.


• Blood spread:– Venous invasion may allow tumor cells be carried via

the portal venous system to the liver. Tumorembolization also occurs through lumbar andvertebral veins to the lungs and elsewhere.Metastases to ovaries are mostly hematogenous; theyare found in 1–10% of women with colorectal cancer.An attempt is made to avoid producing hematogenousmetastases during operation by minimizingmanipulation of the tumor prior to ligation of theblood supply.


• Transperitoneal spread:– "Seeding" may occur when the tumor has extended

through the serosa and tumor cells enter the peritonealcavity, producing local implants or generalized abdominalcarcinomatosis. Large metastatic deposits in the pelvic cul-de-sac are palpable as a hard shelf (Blumer's shelf).

• Intraluminal spread:– Malignant cells shed from the surface of the tumor can be

swept with the fecal current. Implantation more distally onintact mucosa occurs rarely, if ever, but viable exfoliatedcells presumably can be trapped in an anastomotic sutureor staple line during operation.


• Complications:1. Intestinal obstruction:

1. chronic obstruction is common especially in left colon cancer (20%). This tendency is attributed to:1. The smaller lumen of the left colon.2. Stool tends to be more solid.3. Carcinoma tends to be of the stenosing type.

2. Acute obstruction may occur due to faecal impaction or intussusception (in carcinoma at the ileocaecal valve and sigmoid colon).

2. Haemorrhage: Chronic bleeding is the rule and causes iron deficiency anaemia. Massive bleeding is rare.

3. Perforation: is rare and is usually gradual with the formation of a pericolic abscess and faecal fistula.

4. Malignant ascites: results from liver secondaries, lymph nodes compressing the portal vein and Transperitoneal spread.


• Staging:– Colorectal cancer staging is based upon tumor depth

and the presence or absence of nodal or distant metastases.

– Old staging systems, such as the Dukes' Classification and its Astler-Coller modification, have been largely replaced by the TNM staging system (Table=).

– The preoperative evaluation usually identifies stage IV disease. In colon cancer, differentiating stages I, II, and III depends upon examination of the resectedspecimen. In rectal cancer, endorectal ultrasound may predict the stage .


• Tumor Stage (T) Definition– Tx Cannot be assessed– T0 No evidence of cancer– Tis Carcinoma in situ– T1 Tumor invades submucosa– T2 Tumor invades muscularis propria– T3 Tumor invades through muscularis propria into subserosa or into nonperitonealized pericolic tissues– T4 Tumor directly invades other organs or tissues or perforates the visceral peritoneum of specimen

• Nodal Stage (N)– NX Regional lymph nodes cannot be assessed– N0 No lymph node metastasis– N1 Metastasis to one to three pericolic or perirectal lymph nodes– N2 Metastasis to four or more pericolic or perirectal lymph nodes– N3 Metastasis to any lymph node along a major named vascular trunk

• Distant Metastasis (M)– MX Presence of distant metastasis cannot be assessed– M0 No distant metastasis– M1 Distant metastasis present

Stage Grouping

STAGE T N M DUKES[§]

0 Tis N0 M0

I T1 N0 M0 A

T2 N0 M0 A

IIA T3 N0 M0 B

IIB T4 N0 M0 B

IIIA T1-T2 N1 M0 C

IIIB T3-T4 N1 M0 C

IIIC Any T N2 M0 C

IV Any T Any N M1

TNM Staging of Colorectal Carcinoma and 5-Year Survival

Stage TNM 5-Year Survival

I T1-2, N0, M0 70–95%

II T3-4, N0, M0 54–65%

III Tany, N1-3, M0 39–60%

IV Tany, Nany, M1 0–16%


• Clinical features:

– Right colon cancer is more common in females, while left colon cancer is more common in males.

• Clinical features depend upon the location of the tumour, its size, and the presence of metastases.

Rigid Sigmoidoscopy


• A. Right colon cancer:• (Irritative manifestations)

– The usual presentation is vague with anaemia, weakness and loss of weight (Anaemia, Anorexia and Asthenia).

– The patient may present with recurrent attacks of pain in the right iliac fossa.

– A hard mass may be present in the right side of the abdomen. It is differentiated from appendicular mass by the long duration and absence of toxaemia and tenderness. A malignant mass is hard, ill-defined, irregular and fixed.

– The patient does not present by intestinal obstruction as • The lesion is usually of the cauliflower variety.• The contents are liquid.• The lumen of the colon is wide.

– Obstruction occurs, rarely, if the lesion obstructs the ileocaecal valve.


• B. Left colon cancer:• (Obstructive manifestations)

1. The usual presentation is change of bowel habits, usually as progressive constipation, but there may be diarrhoea or attacks of constipation alternating with diarrhoea. These patients are usually diagnosed and treated as having colitis. Spurious diarrhoea (early morning slime) may be present.

2. Large bowel obstruction: The patient may present as acute, subacute or chronic large bowel obstruction. There is constipation, severe abdominal distension but vomiting is late. Carcinoma of the sigmoid colon is a common cause of intestinal obstruction in an elderly patient.

3. Bleeding per rectum: Carcinoma of the left colon is a common cause of fresh bleeding per rectum but it is not a common cause of massive bleeding (compare with diverticular disease and angiodysplasia).

4. Mass in the left side of abdomen: As the lesion is usually of the infiltrating scirrhous type, it rarely presents by a mass. If a mass is palpable, it is usually due to faecal impaction above the tumour.


• Investigations1. Blood picture may reveal microcytic hypochromic anaemia. Sigmoidoscopy is essential in all

patients with altered bowel habit or rectal bleeding. Biopsy is obtained from suspicious le-sions. Total colonoscopy is important to exclude a second higher tumour.

2. Sigmoidoscopy is essential in all patients with altered bowel habit or rectal bleeding. Biopsy is obtained from suspicious lesions. Total colonoscopy is important to exclude a second higher tumour.

3. Barium enema. The tumour appears as a fixed irregular stricture or filling defect. Annular strictures of the left colon show a characteristic "apple core appearance". Even with a palpable rectal cancer, contrast radiography is useful to exclude a second higher tumour.

4. To detect spread liver function tests, abdominal ultrasound (or CT scan), and chest X-ray are done. If the tumour is expected to be close to the ureter, an intravenous urogram (IVU) is essential.

5. Carcinoembryonic antigen (CEA) is a tumour marker whose serum level is high in colorectal cancer but is not specific. It is of prognostic rather than diagnostic value. The level drops after a successful radical surgery. If it shows a rise in the follow up period, this signifies recurrence.

6. For patients presenting with acute intestinal obstruction plain X-ray of the abdomen, blood picture and electrolytes are needed .

Apple core appearance

A double-contrast barium enema showing a carcinoma in the sigmoid colon (The classic apple core defect) .


• Treatment• General principles

– Surgery is the main line of treatment. Radical resection is the only curative measure. For inoperable tumours resection also offers the best palliation.

– Treatment depends on whether the tumour presents by acute obstruction or not and whether the tumour is operable or not.

– Criteria of inoperability 1. Unfit patient.2. Unresectable liver metastases.3. Para-aortic lymph node involvement.4. Peritoneal nodules5. Irresectable primary tumour.


• A. Treatment of colon cancer without acute intestinal obstruction:– Operable cases: elective radical resection. The

operation aims at cure and entails removal of thetumour bearing segment together with its lymphaticdrainage area, in one mass; and then to restore bowelcontinuity. Since the lymph nodes are so close to themain blood vessels arising from the superior andinferior mesenteric, their clearance requires ligationand division of these vessels at their origin, and conse-quently the whole part of the colon supplied by theremoved vessels should be resected.

Polyp Snaring

Principles of Surgical Management of Colo-rectal Ca

As a basic principle, any colorectal cancer is an indication for surgery unlesswidespread tumor dissemination or general contraindications from the patient'soverall health status are present.

The general goal for surgical management is either to achieve cure from the tumorand extension of survival or disease-free survival

Local tumor control generally is the primary treatment objective to prevent localtumor complications, i.e., obstruction, perforation, bleeding, and pain. Even in thepresence of distant metastases in the liver or lung, resection of the primary tumorremains a reasonable priority.

Since solitary or a limited number of metastases in the liver or lung often may betreated surgically by partial organ resection or metastasectomy with a cure rate ofup to 35%, their presence should not necessarily alter the surgical approach at theprimary site to do a curative resection.

In contrast to rectal cancer, neoadjuvant treatment (i.e., preoperativechemoradiation) is not indicated in the overwhelming majority of colonic casesunless a locally very advanced lesion is treated with chemotherapy in anticipationof an otherwise unresectable mass. Adjuvant (i.e., postoperative) treatment will bediscussed in a later section.

Preparation for Surgery

Transfusion: Even though many colonic operations can be performedwithout a blood transfusion, it is recommended to have the patient's bloodtyped and crossed-matched, with a minimum of 2 units of blood availableat the beginning of the surgery.

Bowel Cleansing: the products used generally are based on eitherpolyethylene glycol (e.g., GoLytely) or sodium phosphate (Fleet Phospho-soda), the latter of which is contraindicated in patients with renal failure.

Antibiotic Prophylaxis: Intravenous broad-spectrum antibiotics oftencontain a combination of intravenous second- or third-generationcephalosporin (cefoxitin or ceftriaxone) with metronidazole.

Thromboembolic Prophylaxis Urinary Catheters/Stents Nasogastric Tube: is not necessary on a routine basis for patients

undergoing resection of the colon or rectum unless they present with acomplete or partial bowel obstruction.166

Preoperative Marking of Ostomy Site


a) Tumours of the caecum or the ascending colon: require a right hemicolectomy: The terminal 10 inches of the ileum, the caecum, the ascending colon, the hepatic flexure, and the right

third of the transverse colon (to the right of the middle colic vessels) are resected. The operation is completed by performing an ileotransverse anastomosis.

b) Tumours of the hepatic flexure: are treated by extended right hemicolectomy, where in addition to the above, the middle colic vessels are included. The resection extends to the junction of the right two thirds and the left third of the transverse colon.

c) Tumours of the transverse colon: are treated by transverse colectomy where the middle colic vessels are divided flush at their origin and the transverse colon is resected with the hepatic and splenicflexures, the transverse mesocolon and the omentum A colocolonic anastomosis is then performed.

d) Tumours of the splenic flexure or the descending colon: are treated by left hemicolectomy: the resection includes the left half of the transverse colon (to the left of the middle colic vessels), the splenic flexure and descending colon .

e) Tumours of the distal transverse colon and splenic flexure: are treated by extended left hemicolectomy, where the left hemicolectomy is extended proximally to include the right branches of the middle colic vessels.

g) Tumours arising in a long redundant sigmoid colon may be treated by sigmoid colectomy, where the sigmoid vessels are divided at their origin from the inferior mesenteric artery and the resection includes the sigmoid colon and mesocolon and sigmoid vessels.

Carcinoma of the colonExtent of resection for carcinoma of the colon. A. Caecal and right colonic

cancer. B. Hepatic flexure cancer. C. Transverse colon cancer. D. Splenicflexure cancer.

Carcinoma of the colonExtent of resection for carcinoma of the colon . E. Descending

colon cancer. F. Sigmoid colon cancer.


– Palliative operations for Inoperable cases : (whether inoperability is diagnosed before or during operation)• Whenever possible, palliative resection of the colon cancer

is preferred. Here there is no need for wide resection of the bowel nor its lymphatics and vessels. The operation is destined to obviate the risk of obstruction and bleeding.

• Tumours of the right colon require a side to side ileo-transverse anastomosis.

• Tumours elsewhere in the colon require a proximal colostomy.

– After palliative surgery, radiotherapy, chemotherapy (5-flurouracil) and immunotherapy may be given to the patient.


• B. Treatment of colon cancer with acute intestinal obstruction:– Urgent surgery is required after adequate resuscitation. – The best is colon resection (radical or palliative depending on operability).– If the lesion is in the right colon, primary resection anastomosis is feasible .If

the tumour is in the left colon, the proximal end of the colon is brought to the surface as end colostomy. The distal end is either closed as a Hartmann s pouch or brought to the surface as a mucous fistula.

– N>B: Nowadays obstructed left colon cancer can be treated by resection and primary anastomosis because it has a better prognosis as it allows earlier removal of the tumour. The proximal colon should be decompressed and cleaned by on-table lavage before anastomosis is done.

– Irresectable tumours of the right colon are treated by ileotransverseanastomosis. Irresectable tumours of the left colon are treated by palliative transverse or pelvic colostomy.

– For the critically ill, a proximal colostomy is all that can be done. After relief of obstruction, most colonic carcinomas can be resected at a second-look operation.

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كلية الطب · "polyp" is a morphologic term, and no histologic diagnosis is...

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