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Polyps, DALMs & Megacolon: Polyps, DALMs & Megacolon: Pathology and Imaging of the Colon and RectumPathology and Imaging of the Colon and Rectum

Angela D. Levy and Leslie H. SobinWashington, DC

Drs. Levy and Sobin have indicated that they have no relationships which, in the context of their presentation, could be perceived as a potential conflict of interest.

Polyps, DALMs & MegacolonPolyps, DALMs & MegacolonObjectivesObjectives

1- to present the imaging, classification, and morphology of colorectal polyps

2- to describe DALMs and their significance

3- to present the morphology and imaging of megacolon

Imaging Evaluation of PolypsImaging Evaluation of Polyps

• Epithelial– Sessile – Pedunculated– Filiform

• Subepthelial

CT Colonography: Sessile AdenomaCT Colonography: Sessile Adenoma

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Courtesy of J.R. Choi, Sc.D., M.D.

CT Colonography: Sessile AdenomaCT Colonography: Sessile Adenoma

CT Colonography: Pedunculated AdenomaCT Colonography: Pedunculated Adenoma

CT Colonography: Flat AdenomaCT Colonography: Flat Adenoma

Courtesy of J.R. Choi, Sc.D., M.D.

CT Colonography: Flat AdenomaCT Colonography: Flat Adenoma

Courtesy of J.R. Choi, Sc.D., M.D.

Villous AdenomaVillous Adenoma

Villous AdenomaVillous Adenoma

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Courtesy of J.R. Choi, Sc.D., M.D.

CT CT ColonographyColonography: : AdenocarcinomaAdenocarcinoma

Courtesy of J.R. Choi, Sc.D., M.D.

CT CT ColonographyColonography: : AdenocarcinomaAdenocarcinoma

Annular Annular AdenocarcinomaAdenocarcinoma

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Ulcerative Colitis: Ulcerative Colitis: PseudopolypsPseudopolyps

LipomaLipoma

LipomaLipoma

Rectal Rectal CarcinoidCarcinoid

Rectal GISTRectal GIST

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Intestinal PolypsIntestinal Polyps

• Adenomas• Hyperplastic polyps• Peutz-Jeghers polyps• Juvenile polyps• Inflammatory polyps• Others

Colon: Normal mucosa

Adenoma - subtypes

>20%

Tubular adenoma

Dysplasia starts at the lumen

Tubular adenoma

Villous adenoma

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Sessile Pedunculated

Villous and tubular adenomas

Tubular 71.9%

Tubulovillous22.5%

Villous5.5%

Colorectal adenomas - frequency

Tubular adenoma, low-grade dysplasia

Good nuclear polarity, little mucin reduction, orderly glands

Adenoma, high-grade (severe) dysplasia

Nuclei reach gland surface

Adenoma, high-grade dysplasia (CIS)

Cribriform glands; no invasion beyond mucosa

Colorectal Carcinoma Arising in an Colorectal Carcinoma Arising in an AdenomaAdenoma

• In situ

• Intraepithelial High-grade dysplasia

• Intramucosal

• Invasive = submucosal invasion

[Prevents over-treatment]

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Flat tubular adenoma

No higher than 2x the mucosal thickness

Invasive carcinoma goes to deep margin

Adenocarcinoma arising in a

flat adenoma

Mucin-filled cystic mass in submucosa of polyp’s stalk

Tubular adenoma with pseudoinvasion

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Intestinal PolypsIntestinal Polyps

• Adenomas• Hyperplastic polyps• Serrated polyps• Peutz-Jeghers polyps• Juvenile polyps• Inflammatory polyps

Elongated, straight tubules

Hyperplastic polyp, colon

Serrated adenoma (traditional)

Nuclear stratification of adenoma & serrated profiles of hyp polyp

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Sessile serrated polyp/adenoma

Dilated, horizontal deep glands

Sessile serrated polyp/adenoma

Long >1 cm sessile flat lesion (low power of previous slide)

Sessile Serrated AdenomasSessile Serrated AdenomasHigh risk precursors of microsatellite unstable High risk precursors of microsatellite unstable

colon carcinomascolon carcinomas

• right sided, usually • large, sessile (> 1 cm)• architectural disorder • decreased expression of mismatch repair

proteins: MLH1, MSH2, etc• up to 15% risk of subsequent carcinoma or

high grade dysplasia, esp in rt colon

Genetic PathwaysGenetic Pathways

Tumor suppressor = 85%; Microsatellite = 15% of sporadic adenomas/carcinomas

Serrated PolypsSerrated Polyps

• Hyperplastic polyp • Serrated adenoma (traditional) – localized

lesion; eosinophilic cytoplasm • Sessile serrated adenoma – large, sessile;

disorganized architecture

Sessile ‘adenoma’ rather than sessile ‘polyp’ensures follow-up

Intestinal PolypsIntestinal Polyps

• Adenomas• Hyperplastic polyps• Peutz-Jeghers polyps• Juvenile polyps• Inflammatory polyps

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Peutz-Jeghers polyps

Upright due to muscular infrastructure

Peutz-Jeghers polyp, colon,

Arborizing muscle, little lamina propria, overactive glands

Colon: Peutz-Jeghers polypPeutz-Jeghers polyp, colon

Arborizing muscle, little lamina propria, overactive glands

Peutz-Jeghers polyp, pseudoinvasion, jejunum

Mucosal penetration into muscularis propria

Intestinal PolypsIntestinal Polyps

• Adenomas• Hyperplastic polyps• Peutz-Jeghers polyps• Juvenile polyps• Inflammatory polyps

Juvenile polyp, colon

Round, eroded, expanded lamina propria, cystic dilatation, no muscle, inflamed

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Juvenile polyp (polyposis) - colon

Unusual forms occur in juvenile polyposis, as does dysplasia

Intestinal PolypsIntestinal Polyps

• Adenomas• Hyperplastic polyps• Peutz-Jeghers polyps• Juvenile polyps• Inflammatory polyps

Inflammatory polyp, colon

Granulation tissue polyp

Post-inflammatory polyps (Crohn) - colon

Up-ended mucosa due to ulceration and irregular repair

Post- inflammatory polyps, colon

Result of ulcer healing and repair of up-ended pieces

Post- inflammatory polyps, colon

Mucosa looks healed. Rigidity can cause obstruction

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Post- inflammatory polyps (Crohn)

Rigidity caused obstruction

Ulcerative colitis - pseudopolyps

Ulcerative colitis, pseudopolyps

Mucosal remnants adjacent to ulcers

Inflammatory cloacogenic polyp(Prolapse polyp)

Squamous collar, glandular core, eroded surface

Inflammatory cloacogenic polyp

Pseudomembrane: mucin and polys

Rectum: Mucosal prolapse syndromeColitis cystica profunda

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Intestinal PolypsIntestinal Polyps

• Adenomas• Hyperplastic polyps• Peutz-Jeghers polyps• Juvenile polyps• Inflammatory polyps• Others

Cronkhite-Canada polyp, colon

Gastrointestinal stromal tumor (GIST)

GIST

CD117+

Leiomyoma, colon

Colon:

Lymphomatoid polyposis

Mantle cell lymphoma

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Endometriosis, descending colon polyp:

Ulcerative Colitis Ulcerative Colitis -- Crohn Crohn

Dysplasia Associated Lesion/Mass

(DALM)vs

Adenoma

Ulcerative ColitisUlcerative ColitisDysplasiaDysplasia

• Pedunculated “adenoma” in colitic area + dysplasia-free stalk = adenoma

• Sessile “adenoma” in colitic area = DALM

• Sessile “adenoma” proximal to colitis = adenoma

• Resectable by polypectomy = adenoma

Adenocarcinoma arising in DALM

Low grade dysplasia at surface, invasive carcinoma below

Adenocarcinoma arising in DALM

Low grade dysplasia overlies invasive carcinoma; raised due to invasion

Adenocarcinoma, Crohn colitis

Low-grade tubuloglandular adenocarcinoma

DALM:

Low-grade surface

dysplasia

Invasive carcinoma

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MegacolonMegacolon

• Acute– Common– Transient, secondary to another disease process

• Chronic– Chronic intestinal pseudoobstruction– Chronic intestinal dilatation without obstruction

MegacolonMegacolon• Congenital

– Hirschsprung’s disease• Acquired

– Idopathic– T. cruzi (Chaga’s disease)– Diabetes– Myexdema– Chronic intestinal pseudoobstruction– Toxic megacolon

MegacolonMegacolon

• Imaging evaluation– Typical colonic diameters for diagnosis

• Cecum > 12 cm• Ascending and transverse > 8 cm• Descending and sigmoid > 6 cm

– Radiography• Exclude obstruction

– CT• Wall thickening• Extraintestinal disease

HirschsprungHirschsprung’’s Diseases Disease

HirschsprungHirschsprung’’s Diseases Disease

ChagaChaga’’s Diseases Disease

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Chronic Idiopathic Intestinal Chronic Idiopathic Intestinal PseudoobstructionPseudoobstruction

Hereditary Visceral MyopathyHereditary Visceral Myopathy

Toxic MegacolonToxic Megacolon--Ulcerative ColitisUlcerative Colitis

Toxic MegacolonToxic Megacolon--Ulcerative ColitisUlcerative Colitis

Megacolon