Polyp

Polyp(Tumours) of small intestine and colon

Polyp

Definition: Any growth or tumour mass that protudes into lumen of gut.

Sessile polyp: without definable stalkPedunculated polyp: With stalk.

Polyp (Tumor) of intestine and colon

1.Non neoplastic polyp • Hyperplastic polyps• Hamartomatous Polyps

• Juvenile polyps• Peutz-jeghers polyp

• Inflammatory polyp• Lymphoid polyp

2.Neoplastic epithelial lesionBenign-Adenoma

TubularVillousTubularvillous

-MalignantAdenocarcinomaCarcinoid tumour

Mesenchymal lesionGIST (gastrointestinal stromal tumour)

Others:LipomaAngioma.

- Non neoplastic polyp- They may be formed as the result of abnormal mucosal maturation, inflammation or architecture. They do not have malignant potential.

Neoplastic polyp: that arise as the result of proliferation and dysplasia: termed adenomatous polyp.

True neoplastic polyp are precursor of carcinoma.

Hyperplastic polyp

Morphology:Site: rectosigmoid colonSmall epithelial polyp (nipple like)- less than

5mm,Microscopic:i.Composed of well formed glands and crypts-

lined by non neoplastic epithelial cells with goblet cells.

ii. Serrated or saw toothed appearance: infolding and crowding epithelial cells – due to delayed shedding of surface epithelial cells.

FIGURE : Hyperplastic polyp. A, Polyp surface with irregular tufting of epithelial cells. B, Tufting results from epithelial overcrowding. C, Epithelial crowding produces a serrated architecture when glands are cut in cross-section

Juvenile polyp

Hamartomatous malformation of the mucosal epithelium and lamina propria.

Age: less than 5 yrsAlso called retention polyp: Gross: Site: Rectum1-3cm in diameter -Rounded, smooth with

pedenculated

Microscopic; -Abundant cystically dilated glands – lined by

normal mucous secreting glands.-Cystic spaces: Filled with mucin and

inflammatory debris.-Ulceration and congestion-Stroma-inflammation.

FIGURE : Juvenile polyposis. A, Juvenile polyp. Note the surface erosion and cystically dilated crypts. B, Inspissated mucous, neutrophils, and inflammatory debris can accumulate within dilated crypts.

Whole-mount view of a juvenile (retention) polypCystically dilated glands in an edematous stroma

Peutz-jeghers polyps

Hamartomatous polyps that involves mucosal epithelium, lamina propria and muscularis mucosa

Autosomal dominant disorder:Gross: Large and pedunculated mass with

lobulated contour.

Microscopic:Arborizing network of connective tissue and well

developed smooth muscle extends into polypIt surrounds normal abundant glands lined by

intestinal epithelium.

Figure : Non-neoplastic colonic polyps. A, Hyperplastic polyp; high-power view showing the serrated profile of the epithelial layer. B, Peutz-Jeghers polyp; low-power view showingthe splaying of smooth muscle into the superficial portion of the pedunculated polyp.

Inflammatory polyp

Inflammatory polyp or pseudopolyp results from re-epitheliasiation of ulcer.

Gross: multiple cylindrical to rounded massSize: few mm to few centimeters.Microscopic: Core of polyp consist of inflammatory cells

infiltrate with regenerating epithelium.

Lymphoid polyp..

Reactive hyperplasia of lymphoid tissue results in lymphoid polyps.

Gross: -Site: Rectum-Solitary or multipleMicroscopic:-Composed of prominent lymphoid follicles with

germinal centers.

Adenoma (Adenomatous polyp)

Intraepithelial neoplasm that range from small pedunculated lesion to large neoplasm.

All adenomatous lesions arise as the result of epithelial proliferation and dysplasia.

There is strong evidence that adenomas are a precursor lesion for invasive colorectal adenocarcinoma.

The malignant risk with an adenomatous polyp is correlated with three features

.

Polyp size: cancer is rare in tubular adenomas smaller than 1cm in diameter

Architecture: cancer is high in villous adenomas if the size is more than 4cm in diameter.

Epithelial dysplasia: Sever dysplasia is present in villous adenomas.

Three subtypes:1. Tubular adenonas: tubular glands- more than

75% tubular architecture2. Villous adenomas: Villous projection: Contains

more than 50% villous architecture3. Tubulovillous adenomas: contain 25% to 50%

villous architecture

Tubular adenomas

Gross: Site: 90% in colonSingle or multipleSize: vary in size from less than 1cm to 2.5cm smooth to lobulated contoured and sessile

Microscopic: Composed of neoplastic ( dysplastic) epithelium

which lines the glands. Epithelium: tall, enlarged hyperchromatic and

stratified nuclei with loss of polarity.Stalk is composed of fibromuscular tissue and

prominent blood vessels.

Pedunculated adenoma showing a fibrovascular stalk lined by normal colonic mucosa and a head that contains abundant dysplastic epithelial glands, hence the blue color with the H & E stain. B, A small focus of adenomatous epithelium in an otherwise normal (mucin-secreting, clear) colonic mucosa, showing how the dysplastic columnar epithelium(deeply stained) can populate a colonic crypt and create a tubular architecture

Villous adenomas

Site: Rectum and rectosigmoid colon but may be located elsewere.

Size: sessile up to 10cm in diameterVelvety or cauliflower like projection above the

surrounding mucosa.

Microscopic:Villiform extension of mucosa –covered by

dysplastic epithelium

Tubulovillous adenomas

Intermediate between the tubular and villous lesion.

Gross: Sessile or pedunculated Size: ranging from 0.5 to 5cmMicroscopic: Mixed pattern both tubular and villous pattern.

Gross: Adenopatous Polyp

Various gross appearances of adenomatous villoglandular polyps. A, Sessile polyp. B Pedunculated polyps

Microscopic:Adenopatous polyp

Adenomatous polyp showing marked contrast between the dysplastic glands of the polyp and adjacent normal glands.

In this portion of the adenomatous polyp the dysplastic changes are sharply segregated from the normal goblet cells

Villous adenoma: Gross and Microscopic

Gross appearance of villoglandular polyp Microscopic appearance of villoglandular polyp. There is an admixture of villous and glandular structures

Low-power microscopic appearance of villous adenoma. Long villi are arranged in parallel, perpendicular to the mucosa..Gross appearance of villous adenoma..

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