L17 neoplastic polyps
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Neoplastic Polyps
Lecture 17
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Polyp• A polyp is a mass that
protrudes into the lumen of the gut.
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Tumors of the Small and Large Intestines
Non-neoplastic Polyps 90%Hyperplastic polyps- most commonHamartomatous polypsJuvenile polypsPeutz-Jeghers polypsInflammatory polypsLymphoid polyps
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• Neoplastic Polyps:• Benign polyps• Adenomas• Malignant lesions (Polyps)
Adenocarcinoma Squamous cell carcinoma of the anus
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Adenomas• A benign epithelial tumor in which the cells
form recognizable glandular structures or in which the cells are derived from glandular epithelium.
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Adenomatous Polyps
By definition they are dysplastic and have
malignant potential Time for development of adenomas to cancer is
about 7 to 10 years.
Adenomas
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Epidemiology of Adenoma Older age is a major risk factor More common in men Large adenomas (> 9mm) may be more
common in African Americans African Americans have a higher risk of right-
sided colonic adenomas and may present with cancer at a younger age (< 50 years) than
Caucasians.
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• There is a well-defined familial predisposition to sporadic adenomas, accounting for about a fourfold greater risk for adenomas among first degree relatives, and also a fourfold greater risk of colorectal carcinoma in any person with adenomas.
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Types of adenomas on the basis of the epithelial architecture
• 1. Tubular adenomas• 2. Villous adenomas• 3. Tubulovillous adenomas • 4. Sessile Serrated adenomas
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Endoscopic Classification 1. Sessile – base is attached to colon wall usually
large2. Pedunculated – mucosal stalk is interposed
between the polyp and the wall 3. Flat – height less than one-half the diameter ofthe lesion.
Depressed lesions appear to be particularly likelyto harbor high-grade dysplasia or be malignanteven if small.
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Colonic adenomas. A, Pedunculated adenoma .B, Adenoma with a velvety surface. C, Low-magnification photomicrograph of a pedunculated tubular adenoma.
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Pathologic Classification I. Low grade dysplasiaII. High grade dysplasia
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Tubular Adenoma The most common -- 80%
Characterized by a complex network of branching
adenomatous glands.
Small and pedunculated.
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Morphology of TA
Rectosigmoid -50 %,
Single -50%
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• The smallest adenomas are sessile; • Larger adenomas are pedunculated
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MicroscopyStalk is covered by normal colonic mucosa
Head is composed of neoplastic epithelium, forming
branching glands lined by tall, hyperchromatic, somewhat disorderly
cell, which may or may not show mucin secretion.
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Dysplastic epithelial cells (top) with an increased nuclear-to-cytoplasmic ratio, hyperchromatic and elongated nuclei, and nuclear pseudostratification.
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• In some instances there are small foci of villous architecture.
• In the clearly benign lesion, the branching glands are well separated by lamina propria, and the level of dysplasia or cytologic atypia is slight.
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• However all degrees of dysplasia may be encountered, ranging up to cancer confined to the mucosa (intramucosal carcinoma) or invasive carcinoma extending into the mucosa of the stalk.
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• A frequent finding in any adenoma is superficial erosion of the epithelium,
• the result of mechanical trauma.
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Tubular adenoma with a smooth surface and rounded glands. Active inflammation is occasionally present in adenomas, in this case, crypt
dilation and rupture can be seen at the bottom of the field.
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Villous adenomas
5-15%Glands- long & straight, creating finger-like projections.
large and sessile.
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Morphology of VA
The larger and more ominous. occur in older persons, most commonly in the rectum and rectosigmoid
They generally are sessile, up to 10 cm in diameter, velvety or cauliflower-like masses projecting 1
to 3 cm above the surrounding mucosa.
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Microscopy• frondlike villiform extensions of the mucosa
covered by dysplastic, sometimes very disorderly, sometimes piled-up, columnar epithelium.
• Invasive carcinoma is found in as many as 40% of these lesions,
• the frequency being correlated with the size of the polyp.
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Villous adenoma with long, slender projections that are reminiscent of small intestinal villi.
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Tubulovillous adenomas
26 to 75 % villous component5 to 15 %of adenomas; a broad mix of tubular and villous areas. They are intermediate between the tubular and the
villous lesions in their frequency of having a stalk or being sessile, their size, the degree of dysplasia, and the risk of harboring intramucosal or invasive carcinoma.
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Serrated Polyps Display features of both hyperplastic P and adenomaTwo types Sessile serrated adenoma – precursors to large HP in
proximal colon of patients with hyperplastic polyposis
Traditional serrated adenoma – look and behave as conventional adenomas; often pedunculated found more often in distal colon
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Sessile serrated adenoma lined by goblet cells without typical cytologic features of dysplasia. This lesion is distinguished from a hyperplastic polyp by extension of the
neoplastic process to the crypts, resulting in lateral growth.
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Clinical features of adenomas• The smaller adenomas are usually
asymptomatic, until such time that occult bleeding leads to clinically significant anemia.
• Villous adenomas are much more frequently symptomatic because of overt or occult rectal bleeding.
• The most distal villous adenomas may secrete sufficient amounts of mucosal material rich in protein and potassium to produce hypoproteinemia or hypokalemia.
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• On discovery, all adenomas, regardless of their location in the alimentary tract, are to be considered potentially malignant; thus, in practical terms, prompt and adequate excision is mandated.
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•98% of all cancers in large
intestine almost always arise in
adenomatous polyps, generally curable by resection
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Risk Factors for High grade dysplasia and cancer
Large Size - > 1 cm in diameter are risk factor for containing CRC
Villous histology – adenomatous polyps with > 25percent villous histology are a risk factor for
developing CRC High-grade dysplasia – adenomas with high-grade
dysplasia often coexist with areas of invasive cancer in the polyp.
Number of polyps: three or more is a risk factor
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Adenoma with intramucosal carcinoma. A, Cribriform glands interface directly with the lamina propria without an intervening basement membrane.
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B, Invasive adenocarcinoma (left) beneath a villous adenoma (right). Note the desmoplastic response to the invasive components.
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Plasia
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