Colorectal polyp conditions Notes
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NOTES NOTES COLORECTAL POLYP CONDITIONS GENERALLY, WHAT ARE THEY? PATHOLOGY & CAUSES ▪ Colorectal polyps: overgrowths of epithelial cells lining colon/rectum ▪ Usually benign, can turn malignant TYPES Adenomatous polyps/colonic adenomas ▪ Gland-like polyps caused by tumor suppressor gene mutation in adenomatous polyposis coli (APC) ▪ Characterized by accelerated division of epithelial cells → epithelial dysplasia → polyp formation ▪ No malignant potential by itself; requires mutations in other tumor suppressants (KRAS, p53) ▪ Histologic classiﬁcation ▫ Tubular: pedunculated polyp, protrudes out in lumen ▫ Villous: sessile, cauliﬂower-like appearance; more often malignant ▫ Tubulovillous: characteristics of tubular, villous polyps Serrated polyps ▪ Saw-tooth appearance microscopically ▪ Contain methylated CpG islands → silencing of DNA-repair genes, others → more mutations → malignancy ▫ Small polyps (most common): AKA hyperplastic polyps; rarely malignant ▫ Large polyps: often ﬂat, sessile, malignant Hamartomatous polyps ▪ Mixture of tissues; disorganized mass containing tissue found at site of polyp ▪ Occur sporadically/in genetically inherited conditions (Juvenile polyposis, Peutz– Jeghers syndrome) Inﬂammatory polyps ▪ Caused by inﬂammatory bowel diseases ▫ Crohn’s disease, ulcerative colitis ▪ Not malignant CAUSES ▪ Genetic mutations ▪ Inﬂammatory conditions (e.g. Crohn’s disease) RISK FACTORS ▪ Family history ▪ Bowel wall injury (e.g. radiation exposure, smoking, inﬂammatory bowel disease) ▪ Risk increases with age COMPLICATIONS ▪ Malignancy ▫ Depends on degree of dysplasia, size of polyp SIGNS & SYMPTOMS ▪ Often asymptomatic ▪ If ulcerating ▫ Rectal bleeding, anemia symptoms (e.g. fatigue) ▪ If large ▫ Obstruction → abdominal pain, constipation ▪ Malabsorption → diarrhea ▪ Some polyposis syndromes ▫ Extracolonic symptoms OSMOSIS.ORG 207
DIAGNOSIS TREATMENT DIAGNOSTIC IMAGING SURGERY CT scan, MRI ▪ Hyperdense outpouchings of colonic wall into lumen; detection of metastases Polyp removal (polypectomy) Endoscopy (colonoscopy) with biopsy ▪ Type of polyp, malignant potential (degree of dysplasia) Colonic resection (colectomy) ▪ If multiple polyps associated with polyposis syndromes/polyps with high-grade dysplasia LAB RESULTS ▪ Iron-deﬁciency anemia → decreased red blood cell (RBC) count, low mean corpuscular volume (MCV) levels ▪ Iron-deﬁciency anemia → low ferritin, serum iron, transferrin saturation ▪ APC, RAS, etc. mutations ▪ Assess asymptomatic family members for risk OTHER DIAGNOSTICS Digital rectal examination ▪ Detection of distal rectal polyps; malignant polyp, hard, irregular; benign polyps, softer, pliable Figure 29.2 Histological appearance of a villous adenoma, characterised by a surface composed of long villous projections. 208 OSMOSIS.ORG Figure 29.1 The gross pathological appearance of a sessile colorectal polyp. Figure 29.3 The histological appearance of a tubular adenoma composed of compact glands with variable levels of dysplasia.
Chapter 29 Colorectal Polyp Conditions FAMILIAL ADENOMATOUS POLYPOSIS (FAP) osms.it/familial-adenomatous-polyposis PATHOLOGY & CAUSES ▪ Inherited condition; hundreds/thousands adenomatous polyps in colon ▪ Autosomal dominant inheritance; 100% penetrance; de novo mutations may occur TYPES Classic FAP ▪ Most aggressive, frequent; > 100 polyps at diagnosis; early onset Attenuated FAP (AFAP) ▪ < 100 polyps at diagnosis (oligopolyposis); later onset Autosomal recessive FAP CAUSES ▪ Germline mutation in APC gene (tumor suppressor) → prevention of apoptosis → cell overgrowth → polyps ▪ APC gene nonfunctional in FAP; slightly impaired in AFAP ▪ Autosomal recessive FAP ▫ Mutations of MUTYH gene on chromosome 1 RISK FACTORS ▪ Family history COMPLICATIONS ▪ Malignancy if untreated ▪ Extracolonic manifestations ▫ Congenital hypertrophy of retinal pigment epithelium (CHRPE) ▫ Fundic gland polyps: sessile polyps in stomach, usually not malignant ▫ Duodenal adenomas: malignant potential ▫ Abdominal mesenchymal desmoid tumors: compress adjacent structures → obstruction/vascular impairment ▫ Other potential malignancies: thyroid, pancreas, brain (glioma), liver (hepatoblastoma) SIGNS & SYMPTOMS ▪ Usually asymptomatic until malignancy ▪ Colonic manifestations ▫ Palpable abdominal mass; hematochezia (rectal bleeding); pain (esp. abdomen); diarrhea DIAGNOSIS DIAGNOSTIC IMAGING Endoscopy with biopsy Colonoscopy, ﬂexible sigmoidoscopy: ▪ Detection of ≥ 100 polyps; ~30 polys, AFAP Esophagogastroduodenoscopy (EGD) ▪ Gastric, duodenal adenomas Barium enema (with double contrast) ▪ Filling defects Abdominal CT scan ▪ Hyperdense outpouchings of colonic wall into lumen LAB RESULTS ▪ Iron-deﬁciency anemia ▪ ↓ RBC, ↓ MCV ▪ ↓ ferritin, ↓ serum iron, ↓ transferrin saturation ▪ APC mutations OSMOSIS.ORG 209
OTHER DIAGNOSTICS Family history ▪ Cancers, gastrointestinal (GI) tract diseases Digital rectal examination ▪ Palpable mass Ophthalmic examination ▪ CHRPE TREATMENT MEDICATIONS ▪ Cyclooxygenase 2 inhibitors, other nonsteroidal anti-inﬂammatory drugs (NSAIDs) ▪ Epidermal growth factor receptor inhibitor: erlotinib ▪ Chemotherapy, if colon cancer SURGERY ▪ Frequent endoscopic check-ups to detect onset of polyposis every 1–2 years ▫ If polyps detected → surgical removal (colectomy; proctocolectomy) Figure 29.4 Endoscopic appearannce of the colon in a case of familial adenomatous polyposis. Figure 29.5 A retinal photograph demonstrating hypertrophy of the retinal pigment epithelium in a case of familial adenomatous polyposis. GARDNER'S SYNDROME (GS) osms.it/gardners-syndrome PATHOLOGY & CAUSES ▪ Variant of FAP with prominent extracolonic manifestations ▪ Inherited condition; numerous adenomatous polyps in colon; extracolonic polyps, tumors 210 OSMOSIS.ORG ▪ Tumors outside colon ▫ Fibromas, lipomas, epidermoid cysts, thyroid neoplasms, osteomas, desmoid ▪ Extracolonic polyps can arise in stomach, duodenum, spleen, kidneys, liver, mesentery, small bowel; CHRPE lesions
Chapter 29 Colorectal Polyp Conditions CAUSES ▪ APC, RAS, TP53 mutation; DCC deletion → furthers carcinogenesis ▪ Autosomal dominant inheritance COMPLICATIONS ▪ Malignancy in colon, thyroid, liver, kidneys SIGNS & SYMPTOMS ▪ Colonic manifestations ▫ Rectal bleeding, diarrhea ▪ Extracolonic manifestations ▫ Desmoid tumors (parietal bumps, bleeding) ▫ Dental problems ▫ Epidermoid cysts ▫ Epigastric pain, bleeding, jaundice ▫ Malnutrition → malaise, lethargy, fatigue DIAGNOSIS ▪ Supernumerary impacted teeth ▪ Multiple jaw osteomas, odontomas Digital rectal examination ▪ Palpable mass Ophthalmic examination ▪ CHRPE ECG ▪ Stomach, duodenum for polyps TREATMENT ▪ No cure; palliative treatment SURGERY ▪ Excision of tumors/polyps with wide (8mm) margin ▪ Colectomy OTHER INTERVENTIONS ▪ Radiotherapy, if recurrent DIAGNOSTIC IMAGING Endoscopy with biopsy Colonoscopy, ﬂexible sigmoidoscopy ▪ Direct visualization of adenomatous polyps in colon Abdominal CT scan ▪ Hyperdense outpouchings of colonic wall into lumen Head/dental X-ray ▪ Dental abnormalities LAB RESULTS ▪ Iron-deﬁciency anemia ▫ ↓ RBC, ↓ MCV ▫ ↓ ferritin, ↓ serum iron, ↓ transferrin saturation ▪ Tumoral markers (e.g. carcinoembryonic antigen) ▪ APC, RAS, TP53 mutations; DCC deletion OTHER DIAGNOSTICS Physical examination OSMOSIS.ORG 211
JUVENILE POLYPOSIS SYNDROME osms.it/juvenile-polyposis PATHOLOGY & CAUSES ▪ Numerous benign (AKA juvenile) polyps along GI tract ▪ Majority non-neoplastic hamartomas polyps, in colorectum CAUSES ▪ BMPR1A, SMAD4 mutations ▪ Autosomal dominant inheritance; incomplete penetrance ▪ De novo mutations (25%) COMPLICATIONS ▪ Increased risk of colorectal/extracolonic adenocarcinoma; intestinal obstruction SIGNS & SYMPTOMS ▪ Hematochezia, anemia symptoms; abdominal pain; diarrhea/constipation; rectal prolapse DIAGNOSIS DIAGNOSTIC IMAGING Endoscopic studies ▪ E.g. endoscopy, colonoscopy, sigmoidoscopy ▪ Criteria for diagnosis ▫ > ﬁve juvenile polyps in colon/rectum ▫ Multiple juvenile polyps in other areas of GI tract ▫ Family history with any number of polyps ▪ Biopsy, cytology LAB RESULTS ▪ Iron-deﬁciency anemia ▫ ↓ RBC, ↓ MCV ▫ ↓ ferritin, ↓ serum iron, ↓ transferrin saturation ▪ BMPR1A, SMAD4 mutations TREATMENT SURGERY ▪ Polypectomy ▪ Surgical colectomy, proctocolectomy ▫ Malignant, ulcerating polyps Figure 29.6 A juvenile retention polyp with abundant edematous stroma and dilated cystic spaces ﬁlled with mucin. The spaces are lined by cuboidal epithelium. 212 OSMOSIS.ORG
Chapter 29 Colorectal Polyp Conditions PEUTZ–JEGHERS SYNDROME (PJS) osms.it/peutz-jeghers PATHOLOGY & CAUSES ▪ Inherited condition; benign hamartomatous polyps, in small bowel; also in colon, stomach ▪ Associated with hyperpigmented (melanincontaining) macules on skin, mucosa CAUSES ▪ IV drug use ▫ Increases likelihood of infective endocarditis ▪ Congenital bicuspid aortic valve ▪ Diabetes, high blood pressure, smoking COMPLICATIONS ▪ Very high risk of extracolonic malignant transformation ▫ Breast, ovarian, cervical, testicular, pancreatic, thyroid cancer ▪ Mild malignant potential of polyps SIGNS & SYMPTOMS ▪ GI ▫ Ulceration → GI bleeding (hematochezia/melena) → symptoms of anemia ▫ Colicky abdominal pain ▫ Intussusception → bowel obstruction, bowel infarction ▫ Diarrhea, constipation ▪ Pigmented lesions around oral mucosa, nostrils, perianal area of extremities; fade after puberty DIAGNOSIS DIAGNOSTIC IMAGING Endoscopy, colonoscopy, with biopsy Capsule endoscopy Abdominal CT scan ▪ Hyperdense outpouchings of colonic wall into lumen LAB RESULTS ▪ Fecal occult blood test ▪ Iron-deﬁciency anemia ▫ ↓ RBC, ↓ MCV ▫ ↓ ferritin, ↓ serum iron, ↓ transferrin saturation ▪ Tumor markers ▫ CEA, CA-19-9, CA-125 ▪ STK11 (LKB1) mutations OTHER DIAGNOSTICS Diagnostic criteria ▪ One of following ▫ ≥ two PJ polyps conﬁrmed histologically ▫ ≥ one PJ polyp with family history ▫ PJS-associated mucocutaneous pigmentations Digital rectal examination ▪ Palpable mass TREATMENT SURGERY ▪ Polypectomy MEDICATIONS ▪ Cyclooxygenase 2 inhibitors (celecoxib) OSMOSIS.ORG 213
Figure 29.7 Histological appearance of a Peutz-Jegher’s polyp. 214 OSMOSIS.ORG Figure 29.8 Multiple melanotic macules on the skin and oral mucosa of a young boy with Peutz-Jegher’s syndrome.
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