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Hyperplastic polyps. Hyperplastic polyps are sessile polyps with a diameter of 5-10 mm. Special endoscopic techniques (chro-moendoscopy and "pit pattern classification") must be used to distinguish hyperplastic polyps from adenomas macroscopi-cally.

Hyperplastic polyps, often called metaplastic polyps, are pale or the same color as the surrounding mucosa (09.10 a-d). They usually appear as solitary polyps, but in 5-10% of patients several polyps appear in one colon segment. Larger hyperplastic polyps can be stalked and may be confused with small tubular adenomas.

Histological evaluation is also necessary for hyperplastic polyps. This requires a forceps biopsy or ectomy with histological analysis of the specimen. Histological examination can potentially be avoided in the future, but only if diagnosis based on pit pattern classification is certain and is performed by an examiner experienced in chromoendoscopy and diagnosis.

Juvenile polyps. Juvenile polyps appear in children and adolescents as solitary hamartomatous polyps.

Fig. 9.6 Heterotopic gastric mucosa in rectum with polypoid margin, depression in center.

CT C

t5 c

TO U

Viewed endoscopically, juvenile polyps are up to 3 cm large, with luminous red, friable, eroded, and/or ulcerated surfaces. The surface is occasionally nodular, similar to a tubular adenoma (H 9.10 e, f).

Histologically, these are cystically dilated glands with mucinous material (mucous retention cysts). They are surrounded by increased connective tissue and blood vessels and there is also an increase in inflammatory cells. Though juvenile polyps are not neoplastic per se, there is nonetheless malignant potential if adenomas or mixed juvenile adenomatous polyps appear synchronously (6).

Peutz-Jeghers polyps. Polyps occurring in Peutz-Jeghers syndrome are hamartomas with a characteristic histological appearance of tree branchlike muscularis mucosae.

Peutz-Jeghers polyps can vary in size (up to a few centimeters), and can be stalked or sessile, irregular or lobular (0 9.10 g). The polyp surface can show evidence of infarction. Further details and images can be found in the following section "Polyposis Syndromes."

Inflammatory polyps. Inflammatory polyps are caused by prior colitis attack. They are unspecific and made up of highly inflammatory, focal ulcerations of the epithelium with granulation tissue. More details and images are presented in Chapter 12.

Nonepithelial Polyps

Nonepithelial polyps include submucosal tumors, carcinoid tumors, and also more rare findings such as pneumatosis cys-toides intestinalis or misplaced endometriosal tissue. More information is given in Chapter 11 "Submucosal Tumors" and Chapter 17 "Rare Diseases and Disorders."

Heterotropic gastric mucosa in the rectum is a rare finding. Viewed macroscopically, the polypoid lesion appears to have a raised margin and smooth surface, with a depression in the center (Fig. 9.6).

■ Surveillance

An interdisciplinary consensus panel has made recommendations for endoscopic diagnosis and treatment of polyps that are set forth in the guidelines of the German Society of Digestive and Metabolic Diseases (8). Polyps larger than 5 mm should be removed by polypectomy, while polyps smaller than 5 mm should be resected using forceps. There is no need for special en-doscopic follow-up examination after resection of nonneoplas-tic polyps. Following complete resection of adenomas, surveillance colonoscopy may be required after three years, depending on degree of dysplasia. If no pathologies are found during the first check-up, subsequent check-ups should be performed every five years. Following resection of an adenoma with carcinomatous components (pT1), later check-ups depend on risk classification (low risk/high risk). In the case of partial resection of neoplastic lesions, complete endoscopic or surgical removal of the localized finding should take place as soon as possible. For more information on polypectomy, refer to Chapter 18, "Polypectomy and Mucosectomy."

Polyposis Syndromes

■ Definition

All colorectal polyps that can occur as solitary or multiple polyps can also occur as a polyposis syndrome, with, by definition, more than 100 polyps. A distinction is made between neoplastic and nonneoplastic polyps in polyposis syndromes. Table 9.5 lists neoplastic and nonneoplastic polyposis syndromes.

■ Clinical Picture and Clinical Significance

Though only neoplastic polyposis tends to transform malignantly, there is evidence that nonneoplastic polyposis types such as hamartomas (juvenile polyposis, Peutz-Jeghers polyps) can transform malignantly in isolated cases. In order to classify a polyposis syndrome correctly, it is necessary to completely remove several (generally 5-10) polyps and evaluate them histo-logically.

Familial adenomatous polyposis. Familial adenomatous polyposis (FAP), or familial polyposis coli (FPC), is a hereditary autosomal dominant disease, necessarily precancerous, and by definition characterized by the appearance of more than 100 adenomas. After symptoms appear up to 70% of patients develop a carcinoma, occurring three decades earlier than in the normal population. Gardner syndrome is associated with the related formation of osteomas of the skull, maxilla, and/or mandible, skin lipomas and fibromas, desmoids, and multiple epidermal cysts. Turcot syndrome denotes an association between colonic adenomatous polyposis and tumors of the central nervous system.

Nonneoplastic polyposis syndrome. There are also a number of nonneoplastic polyposis syndromes involving the intestinal tract, e.g., juvenile polyps, Peutz-Jeghers syndrome, and lym-phoid hyperplasia. Polyps occurring in juvenile polyposis are ha-martomas and are similar to solitary juvenile polyps (see above). Around one-third of juvenile polyposis patients have increased frequency of familial occurrence and carcinoma development

Table 9.5 Neoplastic and nonneoplastic polyposis syndromes have not yet been found to be associated with this very rare syndrome.

Cronkhite-Canada syndrome is a nonfamilial disorder that appears after age 40 as a generalized polyposis syndrome of the entire gastrointestinal tract involving cystic degeneration of the mucosa. It is clinically manifested as extremely watery diarrhea, occasionally mixed with blood and mucous, nail atrophy, and alopecia. Prognosis is poor as there is no available causal treatment.

■ Endoscopic Diagnosis

Familial Adenomatous Polyposis (FAP)

Table 9.5 Neoplastic and nonneoplastic polyposis syndromes

Neoplastic polyposis

Nonneoplastic polyposis

syndromes

syndromes

► Familial adenomatous

► Peutz-Jeghers syndrome

polyposis

► Juvenile polyps

► Gardner syndrome

► Cronkhite-Canada syndrome

► Turcot syndrome

► Cowden syndrome

► Inflammatory polyposis

► Benign lymphoid polyposis

► Hyperplastic polyposis

► Pneumatosis cystoides

intestinalis

has been observed in 10% of patients, even though juvenile polyps are nonneoplastic.

Patients with Peutz-Jeghers syndrome have polyps in the entire gastrointestinal tract, mainly in the small intestine. A clinical sign of the syndrome is frecklelike skin pigmentation around the mouth as well as on the mucosa of the lips and mouth. The polyps can be large and can cause significant symptoms like obstruction, bleeding, and intussusception. Though these hamartomatous polyps are not precancerous lesions, carcinomas have been found in the stomach, small intestine, and ovaries.

Cowden syndrome is a hereditary autosomal dominant pol-yposis syndrome that also is marked by hamartomas of the gastrointestinal tract and other organs. Colorectal carcinomas

FAP is characterized endoscopically by multiple polyps, by definition more than 100 adenomas, which cover the colon mucosa in wide swathes. The presence of fewerthan 100 polyps is referred to as an attenuated form of FAP. Generally, adenomas in FAP are 1-3 mm in size and are smooth with a regular border, presenting a normally colored mucosa (0 9.11 a, b). Another variation consists of large sessile and stalked polyps (0 9.11 c, d). Less common is the appearance of larger polyps (4-8 mm) in the entire colon, with normal mucosa in between them. In 70% of patients, one or multiple carcinomas are detected after the appearance of symptoms (0 9.11 e).

Multiple tiny polyps throughout the colon, occurring with Gardner syndrome, are shown in 0 9.12.

~ [F| 9.11 Familial adenomatous polyposis

~ [F| 9.11 Familial adenomatous polyposis a, b Smooth, regular border, sessile adenomas, FAP, 1-3 mm large.

a, b Smooth, regular border, sessile adenomas, FAP, 1-3 mm large.

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