Special polyp types

1. Special polyp types Professor Neil A Shepherd Gloucester, UK NHSBCSP Pathology Day, London, November 21, 2007

2. Pathology and the NHSBCSP • a polyp is any lesion raised above the level of an epithelial surface • suddenly, with BCSP, there are lots more colonoscopies • all done by experts with dye-spray of small lesions and EMR • we might expect to see the occasional funny and we need to be alert

3. A classification of polyps of the colorectum • adenomas • hyperplastic polyps • mixed polyps • inflammatory polyps • juvenile polyps • Peutz-Jeghers polyps • stromal polyps • syndromic polyps – the triumvirate of polyposes, Cowden’s, Cronkhite-Canada, etc Morson & Dawson, 2003

4. A classification of polyps of the colorectum • adenomas • hyperplastic polyps • mixed polyps • inflammatory polyps • juvenile polyps • Peutz-Jeghers polyps • stromal polyps • syndromic polyps – polyposes, Cowden’s, Cronkhite-Canada, etc • but some ‘polyps’ likely to be excised in BCSP are not in the list…..

5. 68M. Polypoid nodule in rectum. chromogranin synaptophysin

6. Gloucestershire BCSP, January-October 2007

7. A classification of polyps of the colorectum • adenomas • hyperplastic polyps • mixed polyps • inflammatory polyps • juvenile polyps • Peutz-Jeghers polyps • stromal polyps • syndromic polyps – polyposes, Cowden’s, Cronkhite-Canada, etc Morson & Dawson, 2003

8. Hyperplastic polyps • about 25% of all polyps Issues: • differentiating them from mixed polyps & serrated adenoma • when they are large and right-sided and show SSP features • when they show epithelial misplacement – inverted hyperplastic polyps

9. Inverted hyperplastic polyps • closely related to right sided SSPs Shepherd, 1991

10. A classification of polyps of the colorectum • adenomas • hyperplastic polyps • mixed polyps • inflammatory polyps • juvenile polyps • Peutz-Jeghers polyps • stromal polyps • syndromic polyps – polyposes, Cowden’s, Cronkhite-Canada, etc Morson & Dawson, 2003

11. Inflammatory polyps • the most common ‘other’ entity in BCSP • most are single/scanty and not related to CIBD (UC, CD, chronic infection such as schisto) • in the age group of the BSCP population, diverticulosis-associated polyps, polypoid mucosal prolapse, post-interventional polyps more common

12. 67F. BCSP. Diverticulosis and sigmoid colonic polyp.

13. Polypoid mucosal prolapse • in the BCSP age group, lower rectal/anal most common: inflammatory cloacogenic polyp • epithelial (villous) hyperplasia traps the unwary into calling them large villous adenomas • may be seen in association with diverticulosis, at stomas, in SUMPS, etc

14. Polypoid mucosal prolapse at the anorectal junction • a word of warning with inflammatory cloacogenic polyp • 4 cases of adenomas of the lower rectum causing secondary polypoid mucosal prolapse Parfitt & Shepherd, 2008

15. a b Ki-67 p53 c d

16. a b Ki-67 p53 d c

17. A classification of polyps of the colorectum • adenomas • hyperplastic polyps • mixed polyps • inflammatory polyps • juvenile polyps • Peutz-Jeghers polyps • stromal polyps • syndromic polyps – polyposes, Cowden’s, Cronkhite-Canada, etc Morson & Dawson, 2003

18. Juvenile polyps • commonest polyp in childhood • sporadic juvenile polyps do occur in adulthood but very rare in BCSP age group • inflammatory polyps can look similar • pretty unlikely to see juvenile polyposis….

19. Juvenile polyposis

20. ‘Atypical juvenile polyps’ with dysplasia

21. Juvenile polyposis • 1 in 80,000 • genetics becoming clearer but polymorphic: SMAD4 implicated in 25% • high rates of colorectal cancer: life time risk - ? up to 30% • dysplasia in atypical juvenile polyps • ? surveillance ? prophylactic colectomy Jass et al 1988, Woodford-Richens et al, 2000

22. Quick quiz question • SMAD 4 mutation is implicated in about a quarter of cases of this condition. What does SMAD stand for? Is it: • somatic mutation in Arctic drosophila • serine-methionine-arginine deletion • small mothers against decapentaplegia

23. Quick quiz question • SMAD 4 mutation is implicated in about a quarter of cases of this condition. What does SMAD stand for? Is it: • somatic mutation in Arctic drosophila • serine-methionine-arginine deletion • small mothers against decapentaplegia

24. A classification of polyps of the colorectum • adenomas • hyperplastic polyps • mixed polyps • inflammatory polyps • juvenile polyps • Peutz-Jeghers polyps • stromal polyps • syndromic polyps – polyposes, Cowden’s, Cronkhite-Canada, etc Morson & Dawson, 2003

25. Peutz-Jeghers polyposis

26. Peutz-Jeghers polyps • syndrome about 1 in 100,000 • sporadic PJ-like polyps described but very rare • ? relationship to ‘inflammatory myoglandular polyp’ • aren’t sporadic PJPs most likely to be post-inflammatory or post-mucosal prolapse?

27. Do sporadic Peutz-Jeghers polyps exist? • 119 polyps in 38 patients • most patients with PJ-like polyps were actually shown to have PJS (scanty colonic polyps in the syndrome) • 8 left: three small bowel ones with PJ features; 5 colonic with suggestive features of PJPs (top GI pathologists could not tell for certain: mucosal prolapse could not be excluded). 40% in BCSP screening age group • if they exist, sporadic colorectal PJ polyps are very rare Burkhart et al. Do sporadic Peutz-Jeghers polyps exist? Experience from a large teaching hospital. AJSP, August 2007

28. A classification of polyps of the colorectum • adenomas • hyperplastic polyps • mixed polyps • inflammatory polyps • juvenile polyps • Peutz-Jeghers polyps • stromal polyps • syndromic polyps – polyposes, Cowden’s, Cronkhite-Canada, etc Morson & Dawson, 2003

29. Stromal polyps • GIST • leiomyoma of muscularis mucosae • gastrointestinal schwannoma • neurofibroma • ganglioneuroma • epithelioid mucosal nerve sheath tumour • intestinal perineurioma • fibroblastic polyp • inflammatory fibroid polyp • that’s enough stromal polyps (Ed)

30. Small polypoid rectal nodules

31. Gastrointestinal schwannoma • 33 cases: 4 oesophagus, 24 stomach, 2 colon and 3 rectum • mainly within muscularis propria and/or subserosa • none encapsulated but all well circumscribed • 32/33 cuff of lymphocytes • only 12 originally called schwannoma • S100 and vimentin +ve • CD117, CD34, ASMA, desmin –ve • nestin 80% positive; GFAP 64% positive • all showed some nuclear pleomorphism: ? longevity: no mitoses • all benign • Hou et al, 2006 (Histopathology)

33. Colonic polypoid mucosal lesions with mucosal entrapment and epithelial serration A feature only rarely seen in GISTs

34. Colorectal intramucosal tumours with epithelial ‘entrapment’

35. Benign fibroblastic polyp of colon:Eslami-Varzaneh F, Washington K, Robert ME, Kashgarian M, Goldblum JR, Jain D. AJSP 2004; 28: 374-378. CD34 positive: ‘neural’ markers negative

36. Intestinal perineurioma:Hornick JL, Fletcher CDM. AJSP 2005; 29: 859-865. EMA positive: CD 117, CD 34, S100 negative

37. Mucosal epithelioid nerve sheath tumour: Lewin MR, Dilworth HP, Alfa AK, Epstein JI, Montgomery E. AJSP 2005; 29: 1310-1315. S 100 CD 34 S100 & CD 34 positive: EMA & CD 117 negative

38. Colorectal intramucosal tumours with epithelial ‘entrapment’ and surface serration • extraordinary ‘new’ descriptions of three entities – smallish spindle cell polypoid tumours with epithelial entrapment and surface epithelial serration • ? recent recognition due to legislation to allow Medicare customers to undergo screening colonoscopy (2001) • lesions are mainly of schwann cell/perineural cell origin • differentiation by immunohistochemistry although specificity of these entities is a little doubtful.. Zamecnik & Chlumska, 2006 Groisman et al, 2006 • all are benign and should not be confused with more sinister lesions such as GISTs and others

39. Take home messages: special polyp types • inflammatory polyp/polypoid mucosal prolapse most common after adenomas and HPs • remember other lesions can be polypoid – leiomyoma of mm and rectal carcinoid – clinical, endoscopic and imaging correlation important • the ‘hamartomatous’ polyps and syndromes are very rare (but not unheard of) in the BCSP age group • serrated change can be a secondary phenomenon (polypoid mucosal prolapse, fibroblastic polyps, etc)