Evaluation Of Colonic Evaluation Of Colonic PolypsPolyps
Kathia E. Rosado Orozco MDKathia E. Rosado Orozco MD
GI and Liver PathologistGI and Liver Pathologist
Hato Rey Pathology Hato Rey Pathology Associates Associates
►Disclosure:Disclosure:
I have no financial disclosures to make.I have no financial disclosures to make. I will suggest texts and websites for I will suggest texts and websites for
reference and study, but receive no reference and study, but receive no financial gain from these.financial gain from these.
Colonic AdenomasColonic Adenomas
►Benign premalignant proliferation of Benign premalignant proliferation of colonic epithelium—all have dysplasia colonic epithelium—all have dysplasia (low grade) and are dysplastic.(low grade) and are dysplastic.
►Precursor lesions to colorectal Precursor lesions to colorectal carcinoma.carcinoma.
ClassificationClassification
►Tubular: less than 25% villousTubular: less than 25% villous►TVA: between 20-80% villousTVA: between 20-80% villous►Villous Adenoma:Villous Adenoma:
Less than 5% of adenomasLess than 5% of adenomas More than 30% have high grade dysplasiaMore than 30% have high grade dysplasia 2% have carcinoma2% have carcinoma
Low grade dysplasia
Colonic AdenomasColonic Adenomas
► 60-70% of all 60-70% of all endoscopically endoscopically removed colonic polypsremoved colonic polyps
► Lifetime prevalence: Lifetime prevalence: 30-50%30-50%
► 50% increase in size 50% increase in size with timewith time
► Only some (5-10%) Only some (5-10%) progress to carcinomaprogress to carcinoma
► 3-5% have invasive 3-5% have invasive carcinoma at diagnosiscarcinoma at diagnosis
► Size of adenoma is Size of adenoma is BEST predictor of BEST predictor of carcinoma riskcarcinoma risk
► High grade dysplasia High grade dysplasia and villous component and villous component more likely with more likely with increase in size of polypincrease in size of polyp
Chromosomal Instability Chromosomal Instability PathwayPathway
High Grade DysplasiaHigh Grade Dysplasia
►Also known as carcinoma in situAlso known as carcinoma in situ►Present in 5-7 % of adenomas at initial Present in 5-7 % of adenomas at initial
diagnosisdiagnosis►More likely if:More likely if:
villousvillous larger (>1cm)larger (>1cm) older than 60 yrsolder than 60 yrs
Intramucosal CarcinomaIntramucosal Carcinoma
►Neoplastic cells extend through gland Neoplastic cells extend through gland basement membrane and into lamina basement membrane and into lamina propria BUT NOT through muscularis propria BUT NOT through muscularis mucosae.mucosae.
►NOT shown to have metastatic risk:NOT shown to have metastatic risk: Paucity of lymphatics in colonic mucosaPaucity of lymphatics in colonic mucosa Classified same as high grade in TNMClassified same as high grade in TNM
Pseudoinvasion in AdenomasPseudoinvasion in Adenomas
►Misplaced or herniated epithelium in Misplaced or herniated epithelium in submucosa.submucosa.
►Can be mistaken for invasive carcinomaCan be mistaken for invasive carcinoma►Most in left colon, particularly sigmoid—Most in left colon, particularly sigmoid—
almost never seen proximal to almost never seen proximal to transverse colontransverse colon
►Pedunculated polyps , more than 1 cm Pedunculated polyps , more than 1 cm with at least 1 cm stalk.with at least 1 cm stalk.
►Peristalsis related torsion/twistingPeristalsis related torsion/twisting
Adenoma with Invasive Adenoma with Invasive AdenocarcinomaAdenocarcinoma
Distinguishing Pseudoinvasion Distinguishing Pseudoinvasion vs. Invasionvs. Invasion
1. Compare the epithelium to epithelium you are 1. Compare the epithelium to epithelium you are confident is adenoma in the same polyp. confident is adenoma in the same polyp. 2. Compare the stroma to stroma you are confident 2. Compare the stroma to stroma you are confident is the benign stroma of adenoma in the same polyp. is the benign stroma of adenoma in the same polyp. 3. Look for evidence of definite vascular or 3. Look for evidence of definite vascular or lymphatic space invasion. lymphatic space invasion. 4. Cut levels. This will at least buy you a little time, 4. Cut levels. This will at least buy you a little time, and you may find more definitive evidence of and you may find more definitive evidence of submucosal invasion in the deeper sections. submucosal invasion in the deeper sections.
Yerian, L. 2010 USCAP short course
-You can call the clinician to discuss the-You can call the clinician to discuss theendoscopic findings and management plan. endoscopic findings and management plan.
-Benign misplaced epithelium is uncommon in -Benign misplaced epithelium is uncommon in sessile lesions. If the polyp was not completely sessile lesions. If the polyp was not completely excised and is not endoscopically resectable, then excised and is not endoscopically resectable, then the patient may need to undergo a resection the patient may need to undergo a resection irrespective of your assessment of the submucosal irrespective of your assessment of the submucosal epithelium. epithelium.
Yerian, L USCAP 2010 Short courseYerian, L USCAP 2010 Short course
PseudoinvasionPseudoinvasion
► Occasionally a definite distinction between Occasionally a definite distinction between invasion and pseudoinvasion is not possible invasion and pseudoinvasion is not possible and consensus cannot be reached, even and consensus cannot be reached, even among experienced GI pathsamong experienced GI paths
► Giving a descriptive diagnosis is best and a Giving a descriptive diagnosis is best and a phone call to the clinician may be helpful. phone call to the clinician may be helpful. The pathologist may choose to describe the The pathologist may choose to describe the finding ("deep neoplastic glands of uncertain finding ("deep neoplastic glands of uncertain significance"), and elaborate in a comment significance"), and elaborate in a comment as to the diagnostic problems. as to the diagnostic problems.
► Yerian, L USCAP 2010 short courseYerian, L USCAP 2010 short course
Carcinomas arising in Carcinomas arising in AdenomasAdenomas
► Surgical resection if: Poorly differentiated at or near margin lymphovascular invasion
► Endoscopic polypectomy is adequate if: carcinoma is low grade (well or moderately
differentiated) margin is free or carcinoma, more than 1 cm
away from margin no evidence of lymphovascular invasion
-Up to 30% in asxs adults over 50 y/o
-Prevalence increases with age
-Usually less than 5mm
-Smooth, sessile
-Typically do not increase in size with time (left sided)
Serrated AdenomasSerrated Adenomas
► Controversial entity only recently recognized Controversial entity only recently recognized (1990) as a pathologic lesion distinct from (1990) as a pathologic lesion distinct from hyperplastic polypshyperplastic polyps
► Recognition due to:Recognition due to: Pts with hyperplastic polyposis have an increased Pts with hyperplastic polyposis have an increased
risk for neoplasiarisk for neoplasia Sporadic right-sided hyperplastic polyps more Sporadic right-sided hyperplastic polyps more
commonly contain a variety of genetic commonly contain a variety of genetic alterations NOT present in left-sided counterparts alterations NOT present in left-sided counterparts
Serrated adenomasSerrated adenomas
►Formal evaluation of their clinical Formal evaluation of their clinical features and incidence is lacking due features and incidence is lacking due to discrepancies in literature in terms to discrepancies in literature in terms of nomenclature--called by numerous of nomenclature--called by numerous namesnames
►Are thought to represent 20% of all Are thought to represent 20% of all lesions with serrated architecture lesions with serrated architecture encountered at endoscopyencountered at endoscopy
Serrated adenomas: FactsSerrated adenomas: Facts
►Epithelial neoplasm with a distinctive Epithelial neoplasm with a distinctive serrated architecture associated with serrated architecture associated with abnormal proliferation and associated abnormal proliferation and associated risk for colorectal neoplasiarisk for colorectal neoplasia
►Slightly more common in left colonSlightly more common in left colon If Small, endoscopic removalIf Small, endoscopic removal
► In right side: In right side: Large (more than 1cm), flatLarge (more than 1cm), flat Remove entirelyRemove entirely Can present as an enlarged foldCan present as an enlarged fold
Serrated polyp neoplasia Serrated polyp neoplasia pathwaypathway
►Proposed to represent an alternative Proposed to represent an alternative molecular pathway to colorectal cancermolecular pathway to colorectal cancer
►Hp--Hp--> > atypical HP--atypical HP-->> serrated adenoma serrated adenoma ---->>cancercancer►Predominant carcinomas of this pathway: Predominant carcinomas of this pathway:
show defective DNA mismatch repair show defective DNA mismatch repair (MMR)—can be MSI high or low(MMR)—can be MSI high or low
►10 to 15% of all colorectal cancers 10 to 15% of all colorectal cancers
MSI and CancerMSI and Cancer
► MSI is a key factor in several cancers including colorectal, MSI is a key factor in several cancers including colorectal, endometrial, ovarian and gastric cancers. Colorectal endometrial, ovarian and gastric cancers. Colorectal cancer studies have demonstrated two mechanisms for cancer studies have demonstrated two mechanisms for MSI occurrence. MSI occurrence.
► The first is in hereditary nonpolyposis colorectal cancer The first is in hereditary nonpolyposis colorectal cancer (HNPCC) or Lynch Syndrome, where an inherited mutation (HNPCC) or Lynch Syndrome, where an inherited mutation in a mismatch-repair gene causes a microsatellite repeat in a mismatch-repair gene causes a microsatellite repeat replication error to go unfixed. replication error to go unfixed.
► The second mechanism whereby MSI causes colorectal The second mechanism whereby MSI causes colorectal cancer is an epigenetic change which silences an essential cancer is an epigenetic change which silences an essential mismatch-repair gene. mismatch-repair gene.
► In both cases, microsatellite insertions and deletions In both cases, microsatellite insertions and deletions within tumor suppressor gene coding regions result in within tumor suppressor gene coding regions result in uncontrolled cell division and tumor growthuncontrolled cell division and tumor growth..
Traditional serrated, usually left-sided
Eosinophilic cytoplasm
Sessile serrated adenoma, right-sided
Sessisle serrated adenoma, right-sided
Neoplasia in serrated polyp Neoplasia in serrated polyp pathwaypathway
►Most if not all sporadic MSI carcinomas Most if not all sporadic MSI carcinomas have a serrated histogenesishave a serrated histogenesis
►Epidemiological association with Epidemiological association with smoking but typical in elderly femalessmoking but typical in elderly females
►Can have several histologic patterns:Can have several histologic patterns: Well to poorly differentiatedWell to poorly differentiated UndifferentiatedUndifferentiated Lymphocytic response Lymphocytic response
-lymphocytic infiltrate
-solid
-signet ring cells
-mucinous
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