Neoplasm of colon

Dr. Amitabha Basu MD

Topic

• Terms

• Classification of neoplasm

• Classification of non-neoplastic polyps

• Discussion on polyps

• Polyps and syndrome

• Discussion on carcinomas

Terms

• Polyp: Mass protruded in lumen– Pedunculated– Sessile

Adenomatous polyps:

a polyp formed by an adenoma.

Classification of neoplasm of colon

1. Non neoplastic polyp

2. Neoplastic lesions

3. Adenomatous polyp

4. Carcinoma

5. Mesenchymal neoplasms

6. Lymphoma

Important Non-neoplastic polyp

Hyperplastic polyps Common, no malignant potential

Hamartomatous polyps

•Juvenile polyps

•Peutz-Jeghers polyps

Hyperplastic polyp

• small star shaped (usually <5 mm in diameter) epithelial polyps like due drop.

• Location: recto sigmoid colon

• No malignant potential

Hamartomatous Polyps

• Juvenile polyps : Focal hamartomatous malformations of mucosa.

• Also called as retention polyps=1 to 3 cm in diameter.

• Tumor composed of Cystically dilated glands.

• Location: colon and rectum • Clinical: spontaneous removal with stool and

blood.

Peutz-Jeghers polyps

• Hamartomatous polyps that involve the mucosal epithelium, lamina propria, and muscularis mucosa.

• Location: mainly small intestine

• Associated with Peutz-Jeghers syndrome.

Neoplastic lesionsAdenomatous polypCarcinomaCarcinoid

Adenomas (adenomatous polyps)

• Tubular adenoma

• Villous adenoma

AdenomaTubular adenoma Villous adenoma

Pedunculated

Colon, Stomach, and small intestine, ampulla of Vater

Large and sessile

Rectum and recto sigmoid colon

75% tubular architecture Villus projection

Cancer is rare More chance of cancer(40%)

Dysplasia:+ Dysplasia ; +++++++++

Presentation: asymptomatic, rectal occult bleeding (+ve guaiac test), Iron deficiency anemia

Tubular adenoma (a Pedunculated

adenoma showing a fibro vascular stalk)

Adenomatous epithelium in an otherwise normal (mucin-secreting, clear) colonic mucosa

diagnosis?

Villous adenoma: sessile adenoma with villous

architecture

Dysplasia present: locate it

Malignant risk with an adenomatous polyp

• Cancer is rare in tubular adenomas < 1 cm in diameter.

• The risk of cancer is high (approaching 40%) in sessile villous adenomas > 4 cm in diameter.

• Severe dysplasia, when present, is often found in villous areas.

Treatment

• Single pedunculated polyp: polypectomy

• Polyposis: complete resection

• Sessile adenoma: recestion

Polyps and syndrome

• Various syndromes are associate with the polyps of the intestine

Familial Polyposis syndrome

• Autosomal dominant.• Number: > 100.• Two syndromes:

– Classic FAP syndrome, patients typically develop 500 to 2500 colonic adenomas.

– Variant of FAP=Gardner syndrome exhibit intestinal polyps identical to those in classic FAP ( + osteoma , epidermal cysts, fibromatosis, CA breast )

Familial Polyposis syndrome

Study other similar picture

Syndromes Altered Gene

Pathology in GI Tract

Familial adenomatous Polyposis

APC ( 5q21) Multiple adenomatous polyps

Hereditary nonpolyposis colorectal carcinoma

AKA: lynch syndrome

Autosomal dominant familial syndrome

Defects in mismatch DNA repair genes → leading to micro satellite instability

Colon cancer, endometrial cancer and fewer/no polyps.

Syndromes

Syndromes Pathology in GI Tract

Peutz-Jeghers syndrome

Hamartomatous polyps+ multiple carcinomas + pigment in mouth, lips

Juvenile polyposis syndrome

Numerous Juvenile polyps

Turcot syndrome Multiple adenomatous polyps, Gliomas.

Cowden disease Hamartomatous polyps + carcinoma breast

Syndromes

Malignant Epithelial Lesions

Adenocarcinoma*

Carcinoid tumor

Colorectal carcinoma: topic

• Features

• Colorectal Carcinogenesis;– Multistep carcinogenesis

• Morphology

Features

• Age: Ages 60 and 79

• Dietary factors:– (1) Excess dietary caloric intake. – (2) A low content of unabsorbable

vegetable fiber, – (3) High content of refined carbohydrates, – (4) Intake of red meat, and – (5) Decreased intake of protective

micronutrients (vitamins A, C, and E )

Adenoma carcinoma sequence: Multistep carcinogenesis

Adenoma carcinoma sequence

1. Loss of Adenomatous Polyposis Coli (APC) Gene(5q21 ) : first hit & second hit: 2 hit theory

2. Mutation of K-RAS + Loss of SMADs + Loss of p53 = adenoma formation.

3. Activation of Telomerase: invasive tumor.

Gross of colon cancer

Proximal colon (right) Distal colon (left)

Polypoid Exophytic masses

Annular, encircling lesions (napkin-ring constrictions )

Obstruction is uncommon.

Obstruction is common.

Develop iron deficiency anemia

No anemia

Carcinoma of the cecum. The fungating carcinoma

projects into the lumen but has not caused obstruction

Carcinoma of the descending colon.

Circumferential tumor has heaped-up edges and an ulcerated central portion.

The arrows identify separate mucosal polyps

Microscopic morphology

• Features of right- and left-sided colonic adenocarcinoma are similar.

• Shows desmoplastic reaction.

• Many tumors produce mucin- PAS positive

• Some cancers the cells take on a signet-ring appearance

Invasive adenocarcinoma of colon, showing malignant glands infiltrating the muscle wall.

Marker and clinical

• CEA ( carcino embryonic antigen)

– Useful for following the course of the disease.

– Stool : occult blood positive ( non specific)

– Alternate Constipation and diarrhea.

Staging of colon carcinoma

• Depends on: size, node involvement and metastasis.

• The Astler-Coller Staging System

• TNM

T

• Tis=Carcinoma in situ (high-grade dysplasia) or intramucosal carcinoma (lamina propria invasion)

• T1=Tumor invades sub mucosa• T2=Extending into the muscularis propria but

not penetrating through it• T3=Penetrating through the muscularis

propria into subserosa• T4=Tumor directly invades other organs or

structures

NM

• Nx= Regional lymph nodes cannot be assessed

• N0=No regional lymph node metastasis• N1=Metastasis in 1 to 3 lymph nodes• N2=Metastasis in 4 or more lymph nodes• Mx=Distant metastasis cannot be assessed• M0=No distant metastasis• M1=Distant metastasis

Grading

• Grade depends on: # of mitosis and differentiation.

• Well differentiated tumor (WD) : good prognosis.

• Small tumor (usually < 2 cm) : usually good prognosis

• Low mitosis (WD): good prognosis• More/ atypical mitosis: bad prognosis

Prognosis depends on Grading and staging – 2 of 2

• Tumor with high mitosis: poor prognosis.• Lymph node involvement : bad prognosis

– (more the number worse is the prognosis)

• Distant metastasis: bad prognosis always.• Poorly differentiated < undifferentiated tumor

< anaplasia : poor prognosis.

Carcinomas arising in the anorectal canal

• Dominated by squamous cell carcinoma.

• Below the ano-rectal junction

• Due to chronic HPV infection

Carcinoid tumors

• Origin: Neuroendocrine cells

• Age: sixth decade

• Appendiceal (commonest) and rectal carcinoids.

• Other sites: Ileal , gastric, and colonic carcinoids.

Morphology The appendix is the most common site.

• Appendicular tumor: Appear as bulbous swellings of the tip, which frequently obliterate the lumen.

• Other place: Bronchus= Intramural masses that create small, polypoid or plateau-like elevations(<3cm)

Remember the size

Colour

• Characteristic feature is a solid, yellow-tan appearance on transection.

• Micro:

– form discrete islands, trabeculae, stands, glands.

– a scant, pink granular cytoplasm and a round to oval stippled nucleus

Multiple protruding tumors are present at the ileocecal junction

Tumor cells exhibit a monotonous morphology (salt and pepper)

Electron micrograph showing dense core bodies in the cytoplasm

Study other similar picture

Clinical Features: many are asymptomatic Malignant carcinoid: mets. to liver

Skin Flushing & diarrhea

Carcinoid syndrome:

By Serotonin

Gastric and pancreatic carcinoids Produce.

Multiple non healing peptic ulcers.

Zollinger-Ellison syndrome

by Gastrin

Cushing syndrome ; hypertension, weight gain, moonfaced.

ACTH

Appendix carcinoid → Obstruction Appendicitis (RUQ pain and neutrophilia)

Diagnosis and prognosis

• Elevated levels of 5-HT and its metabolite, 5-hydroxyindoleacetic acid (5-HIAA), are present in the blood and urine .

• Overall five-year survival rate for carcinoids (excluding appendiceal) is approximately 90%

GASTROINTESTINAL LYMPHOMA

• Definition ::- Primary gastrointestinal lymphomas exhibit no evidence of liver, spleen, mediastinal lymph node, or bone marrow involvement at the time of diagnosis.

• They are nonHodgkins lymphoma(NHL)

Etiology/Risk factors

(1) Chronic gastritis caused by H. pylori

(2) Chronic sprue like syndromes

(3) Natives of the Mediterranean region

(4) Infection with human immunodeficiency virus.

Classification: GASTROINTESTINAL

LYMPHOMA

B-cell lymphoma

MALT lymphoma ; small tumor [t(11;18): translocation common]

Starry sky: bulky tumor

Burkitt lymphoma (t8;14 )

Morphology

• Location:– Stomach, Small intestine, colon

• Gross: plaque-like, with effacement of the overlying mucosal folds and focal ulceration.

• Micro:• Small/Large blue round cell with scanty

cytoplasm.

Melanosis coli

• DEF: Black (brown –black) pigmentation of colon.

• Deposit: Lipofuscin ( “wear and tear”)

• Etiology: laxative use

• Can mimic a tumor/ colitis

• Clinical: constipation.

Thank you