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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