NMS. Casos Clínicos

252

Part II ♦ Specific Disorders

16 cm

Upper third

12 cm

Levator ani muscles

Middle third

8 cm

Lower third

4 cm

Dentate line

2 cm

External sphincter

Anal verge

Figure 8-23: Characteristic appearance of a villous adenoma (sessile polyp) compared with a tubular adenoma (pedunculated polyp). Sessile polyps tend to be more difficult to manage because they are difficult to remove endoscopically and because their malignant potential is greater. (From Lawrence PF. Essentials of General Surgery and Surgical Specialties , 5th ed. Wolters Kluwer Health; 2012, Fig. 15-19.)

Case Variation 8.20.4. Severe atypia in the removed pedunculated polyp ◆ ◆ Polypectomy is sufficient therapy. Close follow-up with colonoscopy is warranted. Case Variation 8.20.5. Carcinoma in situ in the head of a pedunculated polyp with no extension to the stalk ◆ ◆ Polypectomy alone is sufficient therapy in the case of carcinoma in situ confined to the head of a pedunculated polyp because no invasion has occurred through the muscularis mucosa. A bowel resection is not necessary. The long-term risk of lymph node metastasis is about 1–3%. The timing of follow-up is controversial, but the general recommendations are repeat colonoscopy in 3–6 months and then at 12-month intervals. Case Variation 8.20.6. Carcinoma in the stalk of a pedunculated polyp ◆ ◆ The issue of carcinoma in the stalk of the polyp is controversial. Generally, if a margin of greater than 2 mm is present, the cancer is not poorly differentiated or there is no vascu- lar or lymphatic invasion . In such a case, polypectomy is sufficient. Otherwise, marking with a tattoo and surgical resection of that segment of bowel is necessary. Case Variation 8.20.7. Carcinoma in a sessile lesion ◆ ◆ The risk of lymph node metastasis is 15% in sessile polyps with invasive carcinoma . The local recurrence rate following endoscopic resection is about 20% with no further resec- tion, so bowel resection is indicated in this case. Follow-up involves repeat colonoscopy after 1 year. SAMPLE